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Rioux AV, Nsimba-Batomene TR, Slimani S, Bergeron NAD, Gravel MAM, Schreiber SV, Fiola MJ, Haydock L, Garneau AP, Isenring P. Navigating the multifaceted intricacies of the Na +-Cl - cotransporter, a highly regulated key effector in the control of hydromineral homeostasis. Physiol Rev 2024; 104:1147-1204. [PMID: 38329422 DOI: 10.1152/physrev.00027.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 01/01/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024] Open
Abstract
The Na+-Cl- cotransporter (NCC; SLC12A3) is a highly regulated integral membrane protein that is known to exist as three splice variants in primates. Its primary role in the kidney is to mediate the cosymport of Na+ and Cl- across the apical membrane of the distal convoluted tubule. Through this role and the involvement of other ion transport systems, NCC allows the systemic circulation to reclaim a fraction of the ultrafiltered Na+, K+, Cl-, and Mg+ loads in exchange for Ca2+ and [Formula: see text]. The physiological relevance of the Na+-Cl- cotransport mechanism in humans is illustrated by several abnormalities that result from NCC inactivation through the administration of thiazides or in the setting of hereditary disorders. The purpose of the present review is to discuss the molecular mechanisms and overall roles of Na+-Cl- cotransport as the main topics of interest. On reading the narrative proposed, one will realize that the knowledge gained in regard to these themes will continue to progress unrelentingly no matter how refined it has now become.
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Affiliation(s)
- A V Rioux
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - T R Nsimba-Batomene
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - S Slimani
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - N A D Bergeron
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - M A M Gravel
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - S V Schreiber
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - M J Fiola
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - L Haydock
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, INSERM U1151, Université Paris Cité, Paris, France
| | - A P Garneau
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, INSERM U1151, Université Paris Cité, Paris, France
| | - P Isenring
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
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Hernández NEG, Pérez LIE, Aguilera D, Camargo-Muñiz MD, Espinosa CFC, Jaramillo MDLCR, Salvador C, González ZL, Hureaux M, Vargas-Poussou R. Clinical Findings and Genetic Analysis of Nine Mexican Families with Bartter Syndrome. Arch Med Res 2023; 54:102859. [PMID: 37516009 DOI: 10.1016/j.arcmed.2023.102859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/26/2023] [Accepted: 07/04/2023] [Indexed: 07/31/2023]
Abstract
BACKGROUND Bartter's syndrome (BS) is a group of salt-wasting tubulopathies characterized by hypokalemia, metabolic alkalosis, hypercalciuria, secondary hyperaldosteronism, and low or normal blood pressure. Loss-of-function variants in genes encoding for five proteins expressed in the thick ascending limb of Henle in the nephron, produced different genetic types of BS. AIM Clinical and genetic analysis of families with Antenatal Bartter syndrome (ABS) and with Classic Bartter syndrome (CBS). METHODS Nine patients from unrelated non-consanguineous Mexican families were studied. Massive parallel sequencing of a gene panel or whole-exome sequencing was used to identify the causative gene. RESULTS Proband 1 was homozygous for the pathogenic variant p.Arg302Gln in the SLC12A1 gene encoding for the sodium-potassium-chloride NKCC2 cotransporter. Proband 3 was homozygous for the nonsense variant p.Cys308* in the KCNJ1 gene encoding for the ROMK potassium channel. Probands 7, 8, and 9 showed variants in the CLCKNB gene encoding the chloride channel ClC-Kb: proband 7 was compound heterozygous for the deletion of the entire gene and the missense change p.Arg438Cys; proband 8 presented a homozygous deletion of the whole gene and proband 9 was homozygous for the nonsense mutation p.Arg595*. A heterozygous variant of unknown significance was detected in the SLC12A1 gene in proband 2, and no variants were found in SLC12A1, KCNJ1, BSND, CLCNKA, CLCNKB, and MAGED2 genes in probands 4, 5, and 6. CONCLUSIONS Genetic analysis identified loss-of-function variants in the SLC12A1, KCNJ1, and CLCNKB genes in four patients with ABS and in the CLCNKB gene in two patients with CBS.
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Affiliation(s)
- Norma E Guerra Hernández
- Pediatric Nephrology Service, General Hospital of the National Medical Center, La Raza, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Laura I Escobar Pérez
- Department of Physiology of the School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico.
| | - Dora Aguilera
- Pediatric Nephrology Service, General Hospital of the National Medical Center, La Raza, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - María Dolores Camargo-Muñiz
- Department of Pediatrics, Northeast National Medical Center, High Specialty Medical Unit No. 25, Instituto Mexicano del Seguro Social, Monterrey, N.L., Mexico
| | | | | | - Carolina Salvador
- Department of Physiology of the School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Zinaeli López González
- Department of Physiology of the School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Tschernoster N, Erger F, Kohl S, Reusch B, Wenzel A, Walsh S, Thiele H, Becker C, Franitza M, Bartram MP, Kömhoff M, Schumacher L, Kukat C, Borodina T, Quedenau C, Nürnberg P, Rinschen MM, Driller JH, Pedersen BP, Schlingmann KP, Hüttel B, Bockenhauer D, Beck B, Altmüller J. Long-read sequencing identifies a common transposition haplotype predisposing for CLCNKB deletions. Genome Med 2023; 15:62. [PMID: 37612755 PMCID: PMC10464140 DOI: 10.1186/s13073-023-01215-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 07/27/2023] [Indexed: 08/25/2023] Open
Abstract
BACKGROUND Long-read sequencing is increasingly used to uncover structural variants in the human genome, both functionally neutral and deleterious. Structural variants occur more frequently in regions with a high homology or repetitive segments, and one rearrangement may predispose to additional events. Bartter syndrome type 3 (BS 3) is a monogenic tubulopathy caused by deleterious variants in the chloride channel gene CLCNKB, a high proportion of these being large gene deletions. Multiplex ligation-dependent probe amplification, the current diagnostic gold standard for this type of mutation, will indicate a simple homozygous gene deletion in biallelic deletion carriers. However, since the phenotypic spectrum of BS 3 is broad even among biallelic deletion carriers, we undertook a more detailed analysis of precise breakpoint regions and genomic structure. METHODS Structural variants in 32 BS 3 patients from 29 families and one BS4b patient with CLCNKB deletions were investigated using long-read and synthetic long-read sequencing, as well as targeted long-read sequencing approaches. RESULTS We report a ~3 kb duplication of 3'-UTR CLCNKB material transposed to the corresponding locus of the neighbouring CLCNKA gene, also found on ~50 % of alleles in healthy control individuals. This previously unknown common haplotype is significantly enriched in our cohort of patients with CLCNKB deletions (45 of 51 alleles with haplotype information, 2.2 kb and 3.0 kb transposition taken together, p=9.16×10-9). Breakpoint coordinates for the CLCNKB deletion were identifiable in 28 patients, with three being compound heterozygous. In total, eight different alleles were found, one of them a complex rearrangement with three breakpoint regions. Two patients had different CLCNKA/CLCNKB hybrid genes encoding a predicted CLCNKA/CLCNKB hybrid protein with likely residual function. CONCLUSIONS The presence of multiple different deletion alleles in our cohort suggests that large CLCNKB gene deletions originated from many independently recurring genomic events clustered in a few hot spots. The uncovered associated sequence transposition haplotype apparently predisposes to these additional events. The spectrum of CLCNKB deletion alleles is broader than expected and likely still incomplete, but represents an obvious candidate for future genotype/phenotype association studies. We suggest a sensitive and cost-efficient approach, consisting of indirect sequence capture and long-read sequencing, to analyse disease-relevant structural variant hotspots in general.
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Affiliation(s)
- Nikolai Tschernoster
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Florian Erger
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Stefan Kohl
- Department of Pediatrics, Cologne Children's Hospital, Cologne, Germany
| | - Björn Reusch
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Andrea Wenzel
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Stephen Walsh
- Department of Renal Medicine, UCL, University College London, London, UK
| | - Holger Thiele
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Christian Becker
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Marek Franitza
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Malte P Bartram
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
- Department II of Internal Medicine, University of Cologne, Cologne, Germany
| | - Martin Kömhoff
- Department of Pediatrics, University Marburg, Marburg, Germany
| | - Lena Schumacher
- FACS & Imaging Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Christian Kukat
- FACS & Imaging Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Tatiana Borodina
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Hannoversche Straße 28, 10115, Berlin, Germany
| | - Claudia Quedenau
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Hannoversche Straße 28, 10115, Berlin, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Markus M Rinschen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
- Department III of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jan H Driller
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, DK-8000, Aarhus C, Denmark
| | - Bjørn P Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, DK-8000, Aarhus C, Denmark
| | - Karl P Schlingmann
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Bruno Hüttel
- Max Planck Genome-Centre Cologne, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Detlef Bockenhauer
- Department of Renal Medicine, UCL, University College London, London, UK
- Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Bodo Beck
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
| | - Janine Altmüller
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Hannoversche Straße 28, 10115, Berlin, Germany.
- Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Core Facility Genomics, Berlin, Germany.
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Choi N, Kim SH, Bae EH, Yang EM, Lee GH, Lee SH, Lee JH, Ahn YH, Cheong HI, Kang HG, Hyun HS, Kim JH. Long-term outcome of Bartter syndrome in 54 patients: A multicenter study in Korea. Front Med (Lausanne) 2023; 10:1099840. [PMID: 36993809 PMCID: PMC10040751 DOI: 10.3389/fmed.2023.1099840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/16/2023] [Indexed: 03/14/2023] Open
Abstract
IntroductionBartter syndrome (BS) is a rare salt-wasting tubulopathy caused by mutations in genes encoding sodium, potassium, or chloride transporters of the thick ascending limb of the loop of Henle and/or the distal convoluted tubule of the kidney. BS is characterized by polyuria, failure to thrive, hypokalemia, metabolic alkalosis, hyperreninemia, and hyperaldosteronism. Potassium and/or sodium supplements, potassium-sparing diuretics, and nonsteroidal anti-inflammatory drugs can be used to treat BS. While its symptoms and initial management are relatively well known, long-term outcomes and treatments are scarce.MethodsWe retrospectively reviewed 54 Korean patients who were clinically or genetically diagnosed with BS from seven centers in Korea.ResultsAll patients included in this study were clinically or genetically diagnosed with BS at a median age of 5 (range, 0–271) months, and their median follow-up was 8 (range, 0.5–27) years. Genetic diagnosis of BS was confirmed in 39 patients: 4 had SLC12A1 gene mutations, 1 had KCNJ1 gene mutations, 33 had CLCNKB gene mutations, and 1 had BSND mutation. Potassium chloride supplements and potassium-sparing diuretics were administered in 94% and 68% of patients, respectively. The mean dosage of potassium chloride supplements was 5.0 and 2.1 mEq/day/kg for patients younger and older than 18 years, respectively. Nephrocalcinosis was a common finding of BS, and it also improved with age in some patients. At the last follow-up of 8 years after the initial diagnosis, 41% had short stature (height less than 3rd percentile) and impaired kidney function was observed in six patients [chronic kidney disease (CKD) G3, n = 4; CKD G5, n = 2].ConclusionBS patients require a large amount of potassium supplementation along with potassium-sparing agents throughout their lives, but tend to improve with age. Despite management, a significant portion of this population exhibited growth impairment, while 11% developed CKD G3–G5.
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Affiliation(s)
- Naye Choi
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Seong Heon Kim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Eun Hui Bae
- Department of Internal Medicine, Medical School, Chonnam National University, Gwangju, Republic of Korea
| | - Eun Mi Yang
- Department of Pediatrics, Chonnam National University Hospital, Gwangju, Republic of Korea
| | - Geum Hwa Lee
- Department of Pediatrics, Yonsei University Severance Children's Hospital, Seoul, Republic of Korea
| | - Sang-Ho Lee
- Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, Seoul, Republic of Korea
| | - Joo Hoon Lee
- Department of Pediatrics, Ulsan University Asan Medical Center, Seoul, Republic of Korea
| | - Yo Han Ahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Republic of Korea
- Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea
| | - Hae Il Cheong
- Department of Pediatrics, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Republic of Korea
- Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Wide River Institute of Immunology, Seoul National University, Hongcheon, Republic of Korea
| | - Hye Sun Hyun
- Department of Pediatrics, Collage of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
- *Correspondence: Hye Sun Hyun,
| | - Ji Hyun Kim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
- Ji Hyun Kim,
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Abstract
PURPOSE OF REVIEW Gitelman syndrome is a recessive salt-wasting disorder characterized by hypomagnesemia, hypokalemia, metabolic alkalosis and hypocalciuria. The majority of patients are explained by mutations and deletions in the SLC12A3 gene, encoding the Na+-Cl--co-transporter (NCC). Recently, additional genetic causes of Gitelman-like syndromes have been identified that should be considered in genetic screening. This review aims to provide a comprehensive overview of the clinical, genetic and mechanistic aspects of Gitelman(-like) syndromes. RECENT FINDINGS Disturbed Na+ reabsorption in the distal convoluted tubule (DCT) is associated with hypomagnesemia and hypokalemic alkalosis. In Gitelman syndrome, loss-of-function mutations in SLC12A3 cause impaired NCC-mediated Na+ reabsorption. In addition, patients with mutations in CLCKNB, KCNJ10, FXYD2 or HNF1B may present with a similar phenotype, as these mutations indirectly reduce NCC activity. Furthermore, genetic investigations of patients with Na+-wasting tubulopathy have resulted in the identification of pathogenic variants in MT-TI, MT-TF, KCNJ16 and ATP1A1. These novel findings highlight the importance of cell metabolism and basolateral membrane potential for Na+ reabsorption in the DCT. SUMMARY Altogether, these findings extend the genetic spectrum of Gitelman-like electrolyte alterations. Genetic testing of patients with hypomagnesemia and hypokalemia should cover a panel of genes involved in Gitelman-like syndromes, including the mitochondrial genome.
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Affiliation(s)
- Karl P Schlingmann
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Stevenson M, Pagnamenta AT, Mack HG, Savige J, Giacopuzzi E, Lines KE, Taylor JC, Thakker RV. The Bartter-Gitelman Spectrum: Fifty Year Follow-up with Revision of Diagnosis after Whole Genome Sequencing. J Endocr Soc 2022; 6:bvac079. [PMID: 35668994 PMCID: PMC9155595 DOI: 10.1210/jendso/bvac079] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Indexed: 11/26/2022] Open
Abstract
Bartter syndrome (BS) and Gitelman syndrome (GS) are renal tubular disorders affecting sodium, potassium, and chloride reabsorption. Clinical features include muscle cramps and weakness, in association with hypokalemia, hypochloremic metabolic alkalosis, and hyperreninemic hyperaldosteronism. Hypomagnesemia and hypocalciuria are typical of GS, while juxtaglomerular hyperplasia is characteristic of BS. GS is due to SLC12A3 variants, whereas BS is due to variants in SLC12A1, KCNJ1, CLCNKA, CLCNKB, BSND, MAGED2, or CASR. We had the opportunity to follow up one of the first reported cases of a salt-wasting tubulopathy, who based on clinical features was diagnosed with GS. The patient had presented at age 10 years with tetany precipitated by vomiting or diarrhea. She had hypokalemia, a hypochloremic metabolic alkalosis, hyponatremia, mild hypercalcemia, and normomagnesemia, and subsequently developed hypocalciuria and hypomagnesemia. A renal biopsy showed no evidence for juxtaglomerular hyperplasia. She developed chronic kidney failure at age 55 years, and ocular sclerochoroidal calcification, associated with BS and GS, at older than 65 years. Our aim was therefore to establish the genetic diagnosis in this patient using whole-genome sequencing (WGS). Leukocyte DNA was used for WGS analysis, and this revealed a homozygous c.226C > T (p.Arg76Ter) nonsense CLCNKB mutation, thereby establishing a diagnosis of BS type-3. WGS also identified 2 greater than 5-Mb regions of homozygosity that suggested likely mutational heterozygosity in her parents, who originated from a Greek island with fewer than 1500 inhabitants and may therefore have shared a common ancestor. Our results demonstrate the utility of WGS in establishing the correct diagnosis in renal tubular disorders with overlapping phenotypes.
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Affiliation(s)
- Mark Stevenson
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology & Metabolism (OCDEM), Churchill Hospital, University of Oxford, Oxford, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Alistair T Pagnamenta
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Heather G Mack
- Department of Surgery (Ophthalmology), University of Melbourne, Parkville, Australia
| | - Judith Savige
- The University of Melbourne Department of Medicine (Melbourne Health) and Northern Health, Epping, Australia
| | - Edoardo Giacopuzzi
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kate E Lines
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology & Metabolism (OCDEM), Churchill Hospital, University of Oxford, Oxford, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Jenny C Taylor
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology & Metabolism (OCDEM), Churchill Hospital, University of Oxford, Oxford, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford, United Kingdom
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7
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Viering D, Schlingmann KP, Hureaux M, Nijenhuis T, Mallett A, Chan MM, van Beek A, van Eerde AM, Coulibaly JM, Vallet M, Decramer S, Pelletier S, Klaus G, Kömhoff M, Beetz R, Patel C, Shenoy M, Steenbergen EJ, Anderson G, Bongers EM, Bergmann C, Panneman D, Rodenburg RJ, Kleta R, Houillier P, Konrad M, Vargas-Poussou R, Knoers NV, Bockenhauer D, de Baaij JH. Gitelman-Like Syndrome Caused by Pathogenic Variants in mtDNA. J Am Soc Nephrol 2022; 33:305-325. [PMID: 34607911 PMCID: PMC8819995 DOI: 10.1681/asn.2021050596] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/06/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Gitelman syndrome is the most frequent hereditary salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. Gitelman syndrome is caused by biallelic pathogenic variants in SLC12A3, encoding the Na+-Cl- cotransporter (NCC) expressed in the distal convoluted tubule. Pathogenic variants of CLCNKB, HNF1B, FXYD2, or KCNJ10 may result in the same renal phenotype of Gitelman syndrome, as they can lead to reduced NCC activity. For approximately 10 percent of patients with a Gitelman syndrome phenotype, the genotype is unknown. METHODS We identified mitochondrial DNA (mtDNA) variants in three families with Gitelman-like electrolyte abnormalities, then investigated 156 families for variants in MT-TI and MT-TF, which encode the transfer RNAs for phenylalanine and isoleucine. Mitochondrial respiratory chain function was assessed in patient fibroblasts. Mitochondrial dysfunction was induced in NCC-expressing HEK293 cells to assess the effect on thiazide-sensitive 22Na+ transport. RESULTS Genetic investigations revealed four mtDNA variants in 13 families: m.591C>T (n=7), m.616T>C (n=1), m.643A>G (n=1) (all in MT-TF), and m.4291T>C (n=4, in MT-TI). Variants were near homoplasmic in affected individuals. All variants were classified as pathogenic, except for m.643A>G, which was classified as a variant of uncertain significance. Importantly, affected members of six families with an MT-TF variant additionally suffered from progressive chronic kidney disease. Dysfunction of oxidative phosphorylation complex IV and reduced maximal mitochondrial respiratory capacity were found in patient fibroblasts. In vitro pharmacological inhibition of complex IV, mimicking the effect of the mtDNA variants, inhibited NCC phosphorylation and NCC-mediated sodium uptake. CONCLUSION Pathogenic mtDNA variants in MT-TF and MT-TI can cause a Gitelman-like syndrome. Genetic investigation of mtDNA should be considered in patients with unexplained Gitelman syndrome-like tubulopathies.
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Affiliation(s)
- Daan Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Karl P. Schlingmann
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France
| | - Tom Nijenhuis
- Department of Nephrology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Andrew Mallett
- Department of Renal Medicine, Townsville University Hospital, Townsville, Australia,Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Melanie M.Y. Chan
- Department of Renal Medicine, University College London, London, United Kingdom
| | - André van Beek
- Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | | | - Marion Vallet
- Department of Physiological Functional Investigations, Centre Hospitalier Universitaire de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Stéphane Decramer
- Pediatric Nephrology, Internal Medicine and Rheumatology, Southwest Renal Rare Diseases Centre (SORARE), University Children's Hospital, Toulouse, France
| | - Solenne Pelletier
- Department of Nephrology, University Hospital–Lyon Sud, Lyon, France
| | - Günter Klaus
- Kuratorium für Heimdialyse Pediatric Kidney Center, Marburg, Germany
| | - Martin Kömhoff
- University Children's Hospital, Philipps-University, Marburg, Germany
| | - Rolf Beetz
- Johannes Gutenberg Universität Mainz, Zentrum für Kinder- und Jugendmedizin, Mainz, Germany
| | - Chirag Patel
- Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Mohan Shenoy
- Department of Paediatric Nephrology, Royal Manchester Children’s Hospital, Manchester, United Kingdom
| | - Eric J. Steenbergen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Glenn Anderson
- Department of Pathology, Great Ormond Street Hospital for Children National Health Service (NHS) Foundation Trust, London, United Kingdom
| | - Ernie M.H.F. Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carsten Bergmann
- Limbach Genetics, Medizinische Genetik Mainz, Prof. Bergmann & Kollegen, Mainz, Germany,Department of Medicine, Division of Nephrology, University Hospital Freiburg, Germany
| | - Daan Panneman
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Pascal Houillier
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Nine V.A.M. Knoers
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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8
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Schlingmann KP, Jouret F, Shen K, Nigam A, Arjona FJ, Dafinger C, Houillier P, Jones DP, Kleinerüschkamp F, Oh J, Godefroid N, Eltan M, Güran T, Burtey S, Parotte MC, König J, Braun A, Bos C, Ibars Serra M, Rehmann H, Zwartkruis FJ, Renkema KY, Klingel K, Schulze-Bahr E, Schermer B, Bergmann C, Altmüller J, Thiele H, Beck BB, Dahan K, Sabatini D, Liebau MC, Vargas-Poussou R, Knoers NV, Konrad M, de Baaij JH. mTOR-Activating Mutations in RRAGD Are Causative for Kidney Tubulopathy and Cardiomyopathy. J Am Soc Nephrol 2021; 32:2885-2899. [PMID: 34607910 PMCID: PMC8806087 DOI: 10.1681/asn.2021030333] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/07/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Over the last decade, advances in genetic techniques have resulted in the identification of rare hereditary disorders of renal magnesium and salt handling. Nevertheless, approximately 20% of all patients with tubulopathy lack a genetic diagnosis. METHODS We performed whole-exome and -genome sequencing of a patient cohort with a novel, inherited, salt-losing tubulopathy; hypomagnesemia; and dilated cardiomyopathy. We also conducted subsequent in vitro functional analyses of identified variants of RRAGD, a gene that encodes a small Rag guanosine triphosphatase (GTPase). RESULTS In eight children from unrelated families with a tubulopathy characterized by hypomagnesemia, hypokalemia, salt wasting, and nephrocalcinosis, we identified heterozygous missense variants in RRAGD that mostly occurred de novo. Six of these patients also had dilated cardiomyopathy and three underwent heart transplantation. We identified a heterozygous variant in RRAGD that segregated with the phenotype in eight members of a large family with similar kidney manifestations. The GTPase RagD, encoded by RRAGD, plays a role in mediating amino acid signaling to the mechanistic target of rapamycin complex 1 (mTORC1). RagD expression along the mammalian nephron included the thick ascending limb and the distal convoluted tubule. The identified RRAGD variants were shown to induce a constitutive activation of mTOR signaling in vitro. CONCLUSIONS Our findings establish a novel disease, which we call autosomal dominant kidney hypomagnesemia (ADKH-RRAGD), that combines an electrolyte-losing tubulopathy and dilated cardiomyopathy. The condition is caused by variants in the RRAGD gene, which encodes Rag GTPase D; these variants lead to an activation of mTOR signaling, suggesting a critical role of Rag GTPase D for renal electrolyte handling and cardiac function.
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Affiliation(s)
- Karl P. Schlingmann
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - François Jouret
- Division of Nephrology, Department of Internal Medicine, University of Liège Hospital, Liège, Belgium,Interdisciplinary Group of Applied Genoproteomics, Cardiovascular Sciences, University of Liège, Liège, Belgium
| | - Kuang Shen
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts,Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts,Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Anukrati Nigam
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Francisco J. Arjona
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Claudia Dafinger
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Pascal Houillier
- Cordeliers Research Center, Centre National de la Recherche Scientifique (CNRS), ERL8228, Institut National de la Santé et de la Recherche Médicale (INSERM), Sorbonne University, University of Paris, Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris (AP-HP), European Hospital Georges Pompidou, Paris, France,Reference Center for Hereditary Renal Diseases in Children and Adults (MARHEA), Paris, France
| | - Deborah P. Jones
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Felix Kleinerüschkamp
- Department of Pediatric Cardiology, University Children’s Hospital, Münster, Germany
| | - Jun Oh
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nathalie Godefroid
- Division of Pediatric Nephrology, Saint-Luc University Clinics, Catholic University of Louvain, Brussels, Belgium
| | - Mehmet Eltan
- Department of Pediatric Endocrinology and Diabetes, School of Medicine, Marmara University, Istanbul, Turkey
| | - Tülay Güran
- Department of Pediatric Endocrinology and Diabetes, School of Medicine, Marmara University, Istanbul, Turkey
| | - Stéphane Burtey
- Center for Nephrology and Renal Transplantation, Assistance Publique-Hôpitaux de Marseille, Aix-Marseille University, Marseille, France
| | - Marie-Christine Parotte
- Division of Nephrology-Dialysis, Department of Internal Medicine, CHR Verviers East Belgium, Verviers, Belgium
| | - Jens König
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Alina Braun
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Caro Bos
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maria Ibars Serra
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Holger Rehmann
- Department of Molecular Cancer Research, Center for Molecular Medicine, Oncode Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Fried J.T. Zwartkruis
- Department of Molecular Cancer Research, Center for Molecular Medicine, Oncode Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kirsten Y. Renkema
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Karin Klingel
- Cardiopathology, Institute for Pathology and Neuropathology, University Hospital Tübingen, Tübingen, Germany
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,CECAD, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Carsten Bergmann
- Limbach Genetics, Medizinische Genetik Mainz, Mainz, Germany,Division of Nephrology, Department of Medicine, University Hospital Freiburg, Breisgau, Germany
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Bodo B. Beck
- Institute of Human Genetics, University Hospital Cologne and University of Cologne, Faculty of Medicine, Cologne, Germany,Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany,Center for Rare Diseases, Medical Faculty, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Karin Dahan
- Center of Human Genetics, Gosselies, Belgium,Division of Nephrology, Saint-Luc University Clinics, Catholic University of Louvain, Brussels, Belgium
| | - David Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts,Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Max C. Liebau
- Department of Pediatrics and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany,Center for Rare Diseases, Medical Faculty, University of Cologne and University Hospital Cologne, Cologne, Germany
| | - Rosa Vargas-Poussou
- Department of Genetics, AP-HP, European Hospital Georges Pompidou, Paris, France
| | - Nine V.A.M. Knoers
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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9
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Differential diagnosis of classical Bartter syndrome and Gitelman syndrome: Do we need genetic analysis? MARMARA MEDICAL JOURNAL 2021. [DOI: 10.5472/marumj.1012351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Schlingmann KP, Renigunta A, Hoorn EJ, Forst AL, Renigunta V, Atanasov V, Mahendran S, Barakat TS, Gillion V, Godefroid N, Brooks AS, Lugtenberg D, Lake J, Debaix H, Rudin C, Knebelmann B, Tellier S, Rousset-Rouvière C, Viering D, de Baaij JHF, Weber S, Palygin O, Staruschenko A, Kleta R, Houillier P, Bockenhauer D, Devuyst O, Vargas-Poussou R, Warth R, Zdebik AA, Konrad M. Defects in KCNJ16 Cause a Novel Tubulopathy with Hypokalemia, Salt Wasting, Disturbed Acid-Base Homeostasis, and Sensorineural Deafness. J Am Soc Nephrol 2021; 32:1498-1512. [PMID: 33811157 PMCID: PMC8259640 DOI: 10.1681/asn.2020111587] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/04/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The transepithelial transport of electrolytes, solutes, and water in the kidney is a well-orchestrated process involving numerous membrane transport systems. Basolateral potassium channels in tubular cells not only mediate potassium recycling for proper Na+,K+-ATPase function but are also involved in potassium and pH sensing. Genetic defects in KCNJ10 cause EAST/SeSAME syndrome, characterized by renal salt wasting with hypokalemic alkalosis associated with epilepsy, ataxia, and sensorineural deafness. METHODS A candidate gene approach and whole-exome sequencing determined the underlying genetic defect in eight patients with a novel disease phenotype comprising a hypokalemic tubulopathy with renal salt wasting, disturbed acid-base homeostasis, and sensorineural deafness. Electrophysiologic studies and surface expression experiments investigated the functional consequences of newly identified gene variants. RESULTS We identified mutations in the KCNJ16 gene encoding KCNJ16, which along with KCNJ15 and KCNJ10, constitutes the major basolateral potassium channel of the proximal and distal tubules, respectively. Coexpression of mutant KCNJ16 together with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduced currents. CONCLUSIONS Biallelic variants in KCNJ16 were identified in patients with a novel disease phenotype comprising a variable proximal and distal tubulopathy associated with deafness. Variants affect the function of heteromeric potassium channels, disturbing proximal tubular bicarbonate handling as well as distal tubular salt reabsorption.
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Affiliation(s)
- Karl P. Schlingmann
- Department of General Pediatrics, Pediatric Nephrology, University Children’s Hospital, Munster, Germany
| | - Aparna Renigunta
- Department of Pediatric Nephrology, Marburg Kidney Research Center, Philipps University, Marburg, Germany
| | - Ewout J. Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Anna-Lena Forst
- Department of Physiology, Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Vijay Renigunta
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, Marburg, Germany
| | - Velko Atanasov
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Sinthura Mahendran
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | | | - Valentine Gillion
- Division of Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium
| | - Nathalie Godefroid
- Division of Pediatric Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium
| | - Alice S. Brooks
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jennifer Lake
- Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Huguette Debaix
- Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Christoph Rudin
- Department of Pediatric Nephrology, University Children’s Hospital, Basel, Switzerland
| | - Bertrand Knebelmann
- Department of Nephrology-Transplantation, Assistance Publique Hôpitaux de Paris, Hôpital Necker, Paris, France,Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France
| | - Stephanie Tellier
- Department of Pediatric Nephrology, and Rheumatology, French Reference Center of Rare Renal Diseases (SORARE), CHU Toulouse, Toulouse, France,Division of Rheumatology, Department of Pediatrics, Centre Hospitalier Universitaire de Toulouse, Toulouse, France
| | - Caroline Rousset-Rouvière
- Department of Multidisciplinary Pediatrics, Pediatric Nephrology Unit, La Timone, University Hospital of Marseille, Marseille, France
| | - Daan Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H. F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stefanie Weber
- Department of Pediatric Nephrology, Marburg Kidney Research Center, Philipps University, Marburg, Germany
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Pascal Houillier
- Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France,Department of Physiology, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France,Department of Renal Physiology, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale, Sorbonne Université, Université de Paris, Centre National de la Recherche Scientifique, Paris, France
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Olivier Devuyst
- Division of Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium,Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France,Department of Renal Physiology, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale, Sorbonne Université, Université de Paris, Centre National de la Recherche Scientifique, Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France
| | - Richard Warth
- Department of Physiology, Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Anselm A. Zdebik
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom,Department of Renal Medicine, University College London, London, United Kingdom
| | - Martin Konrad
- Department of General Pediatrics, Pediatric Nephrology, University Children’s Hospital, Munster, Germany
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11
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Abstract
Magnesium (Mg2+) plays an essential role in many biological processes. Mg2+ deficiency is therefore associated with a wide range of clinical effects including muscle cramps, fatigue, seizures and arrhythmias. To maintain sufficient Mg2+ levels, (re)absorption of Mg2+ in the intestine and kidney is tightly regulated. Genetic defects that disturb Mg2+ uptake pathways, as well as drugs interfering with Mg2+ (re)absorption cause hypomagnesemia. The aim of this review is to provide an overview of the molecular mechanisms underlying genetic and drug-induced Mg2+ deficiencies. This leads to the identification of four main mechanisms that are affected by hypomagnesemia-causing mutations or drugs: luminal transient receptor potential melastatin type 6/7-mediated Mg2+ uptake, paracellular Mg2+ reabsorption in the thick ascending limb of Henle's loop, structural integrity of the distal convoluted tubule and Na+-dependent Mg2+ extrusion driven by the Na+/K+-ATPase. Our analysis demonstrates that genetic and drug-induced causes of hypomagnesemia share common molecular mechanisms. Targeting these shared pathways can lead to novel treatment options for patients with hypomagnesemia.
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12
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Park SJ, Kim JY, Ahn HJ, Baik HW, Kang JH. Genetic analysis of the Gitelman syndrome coexisting with Osteogenesis imperfecta. Clin Chim Acta 2021; 518:116-122. [PMID: 33775700 DOI: 10.1016/j.cca.2021.03.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/21/2021] [Indexed: 11/28/2022]
Abstract
Gitelman syndrome (GS) is an autosomal recessive disorder caused by loss-of-function mutations in SLC12A3, which encodes the Na-Cl cotransporter (NCC). Osteogenesis imperfecta (OI) is an autosomal dominant disorder caused by the inheritance of mutations mainly in the COL1A1 gene, resulting in bone fragility and deformity. In this study, we aimed to investigate the clinical and genetic manifestations in a 7-year-old boy with OI, who had electrolyte abnormalities and his four family members. Complete sequence analysis of COL1A1 revealed a novel mutation, c.268G>T, p.Glu90del. The gene mutation of OI in the patient's older brother was inherited from his mother, and the younger brother had no mutation. Two pathogenic mutations (c.179C>T, p.Thr60Met and c.1763C>T, p.Ala588Val) in SLC12A3 resulting in GS were also identified in the patient. The OI-related genetic mutation in the patient was consistent with that in the patient's mother. The GS-related genetic mutations were inherited from each parent. This study is the first to identify compound heterozygous variants in the SLC12A3 gene and a novel mutation in the COL1A1 gene in patients with OI and GS. Our findings indicate that genetic analysis is recommended to differentiate GS from BS, as clinical manifestations do not provide an accurate diagnosis.
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Affiliation(s)
- Se Jin Park
- Department of Pediatrics, Eulji University School of Medicine, Daejeon, Republic of Korea
| | - Ju Young Kim
- Department of Pediatrics, Eulji University School of Medicine, Daejeon, Republic of Korea
| | - Hye-Jeong Ahn
- Department of Biochemistry, Eulji University School of Medicine, Daejeon, Republic of Korea
| | - Haing-Woon Baik
- Department of Biochemistry, Eulji University School of Medicine, Daejeon, Republic of Korea.
| | - Ju Hyung Kang
- Department of Pediatrics, Eulji University School of Medicine, Daejeon, Republic of Korea.
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13
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Clinical Characteristics and Gene Mutation Analysis of the Chinese Han Population with Gitelman Syndrome: 3 Case Reports and a Literature Review. Case Rep Med 2020; 2020:6263721. [PMID: 33163079 PMCID: PMC7604593 DOI: 10.1155/2020/6263721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/22/2020] [Accepted: 10/13/2020] [Indexed: 01/19/2023] Open
Abstract
The present study reported clinical characteristics and the results of gene mutation analysis of 3 Chinese patients with Gitelman syndrome (GS). Three patients manifested with normal blood pressure, recurrent hypokalemia, and metabolic alkalosis. Only case 2 had obvious hypomagnesemia. Gene sequencing showed a compound heterozygous mutation in SCL12A3 in case 1 and a homozygous mutation in SCL12A3 in case 2. Heterozygous mutations in SCL12A3 and CLCNKB were found in case 3. Then, the literature was reviewed. The keyword “Gitelman syndrome” was inputted into the PubMed, Wanfang Database, and CNK to search all Chinese patients with GS diagnosed by gene mutations and to extract complete clinical data from December 1998 to 2018. Finally, a total of 124 cases of GS were included. No significant differences in the levels of serum potassium and magnesium were observed among the different gene mutations, and the serum magnesium levels in adults were lower than those of the juvenile. GS with reduced blood magnesium had a serious clinical phenotype. Therefore, GS had a diverse phenotype, and its final diagnosis required genetic profiling. The relationship of gene mutation and clinical phenotype needed further study.
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14
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Figueres L, Prot-Bertoye C, Morla L, Ferriere E, Griveau C, Brideau G, Baron S, Houillier P. Performance of ion chromatography to measure picomole amounts of magnesium in nanolitre samples. J Physiol 2020; 598:5613-5625. [PMID: 32936928 DOI: 10.1113/jp280304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 09/09/2020] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS An UHPLC method to measure picomole amounts of magnesium has been developed. The method is sensitive, specific, accurate and reproducible. The method is suitable for quantifying magnesium transport across intact epithelia. ABSTRACT Magnesium is involved in many biological processes. Extracellular magnesium homeostasis mainly depends on the renal handling of magnesium, the study of which requires measurement of low concentrations of magnesium in renal tubular fluid. We developed an ultra-high-performance liquid chromatography method to measure millimolar concentrations of magnesium in nanolitre samples. Within-assay and between-assay coefficients of variation were lower than 5% and 6.6%, respectively. Measurement of magnesium concentration was linear (r2 = 0.9998) over the range 0-4 mmol/l. Absolute bias ranged from -0.03 to 0.05 mmol/l. The lower limit of quantification was 0.2 mmol/l. Recovery was 97.5-100.3%. No significant interference with calcium, another divalent cation present in the same samples, was detected. The method was successfully applied to quantify transepithelial magnesium transport by medullary and cortical thick ascending limbs during ex vivo microperfusion experiments. In conclusion, ultra-high-performance liquid chromatography is suitable for measurement of picomole amounts of magnesium in renal tubular fluid. The method allows detailed studies of transepithelial magnesium transport across native epithelium.
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Affiliation(s)
- Lucile Figueres
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Caroline Prot-Bertoye
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Centre de référence des maladies rares du calcium et du phosphate, Paris, France
| | - Luciana Morla
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Elsa Ferriere
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Camille Griveau
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Gaëlle Brideau
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Stéphanie Baron
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Centre de référence des maladies rares du calcium et du phosphate, Paris, France
| | - Pascal Houillier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Centre de référence des maladies rares du calcium et du phosphate, Paris, France
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15
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Eder M, Darmann E, Haller MC, Bojic M, Peck-Radosavljevic M, Huditz R, Bond G, Vychytil A, Reindl-Schwaighofer R, Kikić Ž. Markers of potassium homeostasis in salt losing tubulopathies- associations with hyperaldosteronism and hypomagnesemia. BMC Nephrol 2020; 21:256. [PMID: 32631286 PMCID: PMC7336449 DOI: 10.1186/s12882-020-01905-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 06/24/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Renal loss of potassium (K+) and magnesium (Mg2+) in salt losing tubulopathies (SLT) leads to significantly reduced Quality of Life (QoL) and higher risks of cardiac arrhythmia. The normalization of K+ is currently the most widely accepted treatment target, however in even excellently designed RCTs the increase of K+ was only mild and rarely normalized. These findings question the role of K+ as the ideal marker of potassium homeostasis in SLT. Aim of this hypothesis-generating study was to define surrogate endpoints for future treatment trials in SLT in terms of their usefulness to determine QoL and important clinical outcomes. METHODS Within this prospective cross-sectional study including 11 patients with SLTs we assessed the biochemical, clinical and cardiological parameters and their relationship with QoL (RAND SF-36). The primary hypothesis was that QoL would be more dependent of higher aldosterone concentration, assessed by the transtubular-potassium-gradient (TTKG). Correlations were evaluated using Pearson's correlation coefficient. RESULTS Included patients were mainly female (82%, mean age 34 ± 12 years). Serum K+ and Mg2+ was 3.3 ± 0.6 mmol/l and 0.7 ± 0.1 mmol/l (mean ± SD). TTKG was 9.5/3.4-20.2 (median/range). While dimensions of mental health mostly correlated with serum Mg2+ (r = 0.68, p = 0.04) and K+ (r = 0.55, p = 0.08), better physical health was associated with lower aldosterone levels (r = -0.61, p = 0.06). TTKG was neither associated with aldosterone levels nor with QoL parameters. No relevant abnormalities were observed in neither 24 h-ECG nor echocardiography. CONCLUSIONS Hyperaldosteronism, K+ and Mg2+ were the most important parameters of QoL. TTKG was no suitable marker for hyperaldosteronism or QoL. Future confirmatory studies in SLT should assess QoL as well as aldosterone, K+ and Mg2+.
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Affiliation(s)
- Michael Eder
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Elisabeth Darmann
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Maria C Haller
- Institute of Biometrics, Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Vienna, Austria
| | - Marija Bojic
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Markus Peck-Radosavljevic
- Department of Internal Medicine and Gastroenterology (IMuG), Hepatology, Endocrinology, Rheumatology, Nephrology and Emergency Medicine (ZAE), Klinikum Klagenfurt am Wörthersee, Klagenfurt, Austria
| | - Rainer Huditz
- Department of Internal Medicine and Gastroenterology (IMuG), Hepatology, Endocrinology, Rheumatology, Nephrology and Emergency Medicine (ZAE), Klinikum Klagenfurt am Wörthersee, Klagenfurt, Austria
| | - Gregor Bond
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Andreas Vychytil
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Roman Reindl-Schwaighofer
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
| | - Željko Kikić
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria.
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16
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Two novel mutations in the CLCNKBgene leading to classic Bartter syndrome presenting as syncope and hypertension in a 13-year-old boy. BMJ Case Rep 2020; 13:13/7/e233872. [DOI: 10.1136/bcr-2019-233872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Classic Bartter syndrome is a rare condition caused by mutations in theCLCNKBgene and characterised by metabolic alkalosis, hypokalaemia, hyper-reninaemia and hyperaldosteronism. Early signs and symptoms usually occur before a child’s sixth birthday and include polyuria and developmental delay. We treated a 13-year-old Vietnamese boy with this syndrome presenting with atypical presentations including syncope and hypertension, but normal growth and development. All common causes of hypertension were ruled out. Genetic testing found two novel mutations in theCLCNKBgene, that is, Ser12Ala (exon 2) and Glu192Ter (exon 6). His estimated glomerular filtration rate was 61 mL/min/1.73 m2and a kidney biopsy showed focal segmental glomerulosclerosis. He was well managed with long-term enalapril therapy instead of non-steroidalanti-inflammatory drugs which are recommended in managing the increased prostaglandin E2 production in Bartter syndrome. Paediatricians should be alerted with the variability in its presentation. To preserve the kidney function, treatment must include preventing factors damaging the kidneys.
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17
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Sahbani D, Strumbo B, Tedeschi S, Conte E, Camerino GM, Benetti E, Montini G, Aceto G, Procino G, Imbrici P, Liantonio A. Functional Study of Novel Bartter's Syndrome Mutations in ClC-Kb and Rescue by the Accessory Subunit Barttin Toward Personalized Medicine. Front Pharmacol 2020; 11:327. [PMID: 32256370 PMCID: PMC7092721 DOI: 10.3389/fphar.2020.00327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
Type III and IV Bartter syndromes (BS) are rare kidney tubulopathies caused by loss-of-function mutations in the CLCNKB and BSND genes coding respectively for the ClC-Kb chloride channels and accessory subunit barttin. ClC-K channels are expressed in the Henle's loop, distal convoluted tubule, and cortical collecting ducts of the kidney and contribute to chloride absorption and urine concentration. In our Italian cohort, we identified two new mutations in CLCNKB, G167V and G289R, in children affected by BS and previously reported genetic variants, A242E, a chimeric gene and the deletion of the whole CLCNKB. All the patients had hypokalemia and metabolic alkalosis, increased serum renin and aldosterone levels and were treated with a symptomatic therapy. In order to define the molecular mechanisms responsible for BS, we co-expressed ClC-Kb wild type and channels with point mutations with barttin in HEK 293 cells and characterized chloride currents through the patch-clamp technique. In addition, we attempted to revert the functional defect caused by BS mutations through barttin overexpression. G167V and A242E channels showed a drastic current reduction compared to wild type, likely suggesting compromised expression of mutant channels at the plasma membrane. Conversely, G289R channel was similar to wild type raising the doubt that an additional mutation in another gene or other mechanisms could account for the clinical phenotype. Interestingly, increasing ClC-K/barttin ratio augmented G167V and A242E mutants' chloride current amplitudes towards wild type levels. These results confirm a genotype-phenotype correlation in BS and represent a preliminary proof of concept that molecules functioning as molecular chaperones can restore channel function in expression-defective ClC-Kb mutants.
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Affiliation(s)
- Dalila Sahbani
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Bice Strumbo
- Laboratory of Medical Genetics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Silvana Tedeschi
- Laboratory of Medical Genetics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | | | - Elisa Benetti
- Nephrology, Dialysis and Transplant Unit, Department of Women's and Children's Health, University-Hospital of Padova, Padova, Italy
| | - Giovanni Montini
- Pediatric Nephrology, Dialysis, and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | | | - Giuseppe Procino
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
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18
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Han Y, Cheng H, Shao S, Lang Y, Zhao X, Lin Y, Wang S, Shi X, Liu Z, Shao L. Thirteen novel CLCNKB variants and genotype/phenotype association study in 42 Chinese patients with Bartter syndrome type 3. Endocrine 2020; 68:192-202. [PMID: 31834604 DOI: 10.1007/s12020-019-02156-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/02/2019] [Indexed: 12/20/2022]
Abstract
PURPOSE Analyze the genotype of 42 Chinese patients with Bartter syndrome type 3 (BS3) and investigate their correlation between genotype and phenotype. METHODS Identify CLCNKB gene variants by the next-generation sequencing and the multiplex ligation-dependent probe amplification (MLPA), and then evaluate their mutation effects according to 2015 American College of Medical Genetics and Genomics (ACMG) standards and guidelines. RESULTS Thirty-six different variants in CLCNKB gene, including 13 novel ones, were found. The whole gene deletion of CLCNKB gene was the most frequent mutation (40%), and the rate of large deletions is up to 55%. Among 36 variants, six (c.1244T>A, c.1468G>A, c.849_851delCTT, c.359G>T, c.1052G>T, and c.1309G>A) and three (c.228A>C, c.1294_1295TA>CT, and c.1333T>G) variants were classified as "likely pathogenic variants" and "variants with uncertain significance (VUS)," respectively. The other 27 variants were classified as "pathogenic variants". The most common symptoms included: growth retardation (38/42), polydipsia and polyuria (35/42), constipation (31/42), and vomiting (27/42). All patients presented with hypokalemia, hypochloremia, and metabolic alkalosis. The genotype and phenotype association study revealed that who had mutations probably resulting in complete loss of function of both alleles might have severer phenotype. After the treatment that based on indomethacin and potassium chloride, most patients could achieve obvious recovery of growth rate and restoration of hypokalemia. CONCLUSIONS The present study have found 36 variants of CLCNKB gene, including 13 novel ones, which enrich the human gene mutation database and provide valuable references to diagnosis, treatment, and the genetic counseling of Chinese population.
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Affiliation(s)
- Yue Han
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Hai Cheng
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
| | - Shihong Shao
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Yanhua Lang
- Department of Nursing, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Xiangzhong Zhao
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Yi Lin
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Sai Wang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Xiaomeng Shi
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Zhiying Liu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China.
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China.
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19
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Wang X, Ding Y, Liu Q, Yang G. A novel compound heterozygous mutation of SLC12A3 gene in a Chinese pedigree with Gitelman syndrome. Endocrine 2020; 67:673-677. [PMID: 31808035 DOI: 10.1007/s12020-019-02152-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 11/28/2022]
Abstract
PURPOSE Gitelman syndrome (GS) is an autosomal recessive renal tubular disorder characterized by salt wasting and hypokalemia resulting from loss-of-function mutations in the solute carrier family 12A3 (SLC12A3) gene encoding the thiazide-sensitive NaCl cotransporter (NCC). Here, we investigated the clinical manifestations and genetic features of a Chinese pedigree with GS. METHODS Next-generation sequencing and Sanger sequencing analysis were performed to define and confirm the SLC12A3 gene mutations of the patient (proband II:1) and this pedigree. Clinical manifestations and biochemical parameters were collected and analyzed. RESULTS Genetic analysis of the SLC12A3 gene identified two novel mutations in the proband, heterozygous (c.2842delT) and heterozygous (c.1569_1586del) mutation, respectively. Additionally, heterozygous (c.2842delT) mutation in SLC12A3 gene was found in his father and younger brother. The other heterozygous (c.1569_1586del) mutation in SLC12A3 gene was carried by his mother. CONCLUSIONS Two novel mutations may be related to the occurrence of the GS in the pedigree. However, additional studies are particularly required to explore the underlying molecular mechanisms.
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Affiliation(s)
- Xin Wang
- Department of Rheumatology, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), 312000, Shaoxing, People's Republic of China
| | - Yu Ding
- Central Laboratory, Hangzhou First People's Hospital, Zhejiang University School of Medicine, 310006, Hangzhou, People's Republic of China
| | - Qi Liu
- Department of Transfusion, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), 312000, Shaoxing, People's Republic of China.
| | - Guocan Yang
- Department of Transfusion, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), 312000, Shaoxing, People's Republic of China.
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20
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Besouw MTP, Kleta R, Bockenhauer D. Bartter and Gitelman syndromes: Questions of class. Pediatr Nephrol 2020; 35:1815-1824. [PMID: 31664557 PMCID: PMC7501116 DOI: 10.1007/s00467-019-04371-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/28/2019] [Accepted: 09/17/2019] [Indexed: 12/30/2022]
Abstract
Bartter and Gitelman syndromes are rare inherited tubulopathies characterized by hypokalaemic, hypochloraemic metabolic alkalosis. They are caused by mutations in at least 7 genes involved in the reabsorption of sodium in the thick ascending limb (TAL) of the loop of Henle and/or the distal convoluted tubule (DCT). Different subtypes can be distinguished and various classifications have been proposed based on clinical symptoms and/or the underlying genetic cause. Yet, the clinical phenotype can show remarkable variability, leading to potential divergences between classifications. These problems mostly relate to uncertainties over the role of the basolateral chloride exit channel CLCNKB, expressed in both TAL and DCT and to what degree the closely related paralogue CLCNKA can compensate for the loss of CLCNKB function. Here, we review what is known about the physiology of the transport proteins involved in these disorders. We also review the various proposed classifications and explain why a gene-based classification constitutes a pragmatic solution.
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Affiliation(s)
- Martine T. P. Besouw
- Department of Pediatric Nephrology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Robert Kleta
- Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK ,Department of Renal Medicine, University College London, London, UK
| | - Detlef Bockenhauer
- Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK ,Department of Renal Medicine, University College London, London, UK
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21
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Bignon Y, Sakhi I, Bitam S, Bakouh N, Keck M, Frachon N, Paulais M, Planelles G, Teulon J, Andrini O. Analysis of CLCNKB mutations at dimer-interface, calcium-binding site, and pore reveals a variety of functional alterations in ClC-Kb channel leading to Bartter syndrome. Hum Mutat 2019; 41:774-785. [PMID: 31803959 DOI: 10.1002/humu.23962] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/14/2019] [Accepted: 11/29/2019] [Indexed: 12/12/2022]
Abstract
Pathological missense mutations in CLCNKB gene give a wide spectrum of clinical phenotypes in Bartter syndrome type III patients. Molecular analysis of the mutated ClC-Kb channels can be helpful to classify the mutations according to their functional alteration. We investigated the functional consequences of nine mutations in the CLCNKB gene causing Bartter syndrome. We first established that all tested mutations lead to decreased ClC-Kb currents. Combining electrophysiological and biochemical methods in Xenopus laevis oocytes and in MDCKII cells, we identified three classes of mutations. One class is characterized by altered channel trafficking. p.A210V, p.P216L, p.G424R, and p.G437R are totally or partially retained in the endoplasmic reticulum. p.S218N is characterized by reduced channel insertion at the plasma membrane and altered pH-sensitivity; thus, it falls in the second class of mutations. Finally, we found a novel class of functionally inactivated mutants normally present at the plasma membrane. Indeed, we found that p.A204T alters the pH-sensitivity, p.A254V abolishes the calcium-sensitivity. p.G219C and p.G465R are probably partially inactive at the plasma membrane. In conclusion, most pathogenic mutants accumulate partly or totally in intracellular compartments, but some mutants are normally present at the membrane surface and simultaneously show a large range of altered channel gating properties.
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Affiliation(s)
- Yohan Bignon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Imene Sakhi
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Sara Bitam
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Naziha Bakouh
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Mathilde Keck
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | | | - Marc Paulais
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Gabrielle Planelles
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Jacques Teulon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Olga Andrini
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, Lyon, France
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22
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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23
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Adalat S, Hayes WN, Bryant WA, Booth J, Woolf AS, Kleta R, Subtil S, Clissold R, Colclough K, Ellard S, Bockenhauer D. HNF1B Mutations Are Associated With a Gitelman-like Tubulopathy That Develops During Childhood. Kidney Int Rep 2019; 4:1304-1311. [PMID: 31517149 PMCID: PMC6732753 DOI: 10.1016/j.ekir.2019.05.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/29/2019] [Accepted: 05/20/2019] [Indexed: 12/20/2022] Open
Abstract
Background Mutations in the transcription factor hepatocyte nuclear factor 1B (HNF1B) are the most common inherited cause of renal malformations, yet also associated with renal tubular dysfunction, most prominently magnesium wasting with hypomagnesemia. The presence of hypomagnesemia has been proposed to help select appropriate patients for genetic testing. Yet, in a large cohort, hypomagnesemia was discriminatory only in adult, but not in pediatric patients. We therefore investigated whether hypomagnesemia and other biochemical changes develop with age. Methods We performed a retrospective analysis of clinical, biochemical, and genetic results of pediatric patients with renal malformations tested for HNF1B mutations, separated into 4 age groups. Values were excluded if concurrent estimated glomerular filtration rate (eGFR) was <30 ml/min per 1.73 m2, or after transplantation. Results A total of 199 patients underwent HNF1B genetic testing and mutations were identified in 52 (mut+). The eGFRs were comparable between mut+ and mut- in any age group. Although median plasma magnesium concentrations differed significantly between mut+ and mut- patients in all age groups, overt hypomagnesemia was not present until the second half of childhood in the mut+ group. There was also a significant difference in median potassium concentrations in late childhood with lower values in the mut+ cohort. Conclusions The abnormal tubular electrolyte handling associated with HNF1B mutations develops with age and is not restricted to magnesium, but consistent with a more generalized dysfunction of the distal convoluted tubule, reminiscent of Gitelman syndrome. The absence of these abnormalities in early childhood should not preclude HNF1B mutations from diagnostic considerations.
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Affiliation(s)
- Shazia Adalat
- Evelina Children’s Hospital, London, United Kingdom
- UCL Department of Renal Medicine, London, United Kingdom
| | - Wesley N. Hayes
- UCL Department of Renal Medicine, London, United Kingdom
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - William A. Bryant
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - John Booth
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Adrian S. Woolf
- Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, University of Manchester, United Kingdom
- Royal Manchester Children’s Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Robert Kleta
- UCL Department of Renal Medicine, London, United Kingdom
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | | | - Rhian Clissold
- Royal Devon and Exeter NHS Foundation Trust, Exeter, United Kingdom
| | - Kevin Colclough
- Department of Molecular Genetics, Royal Devon & Exeter NHS Foundation Trust, Exeter, United Kingdom
| | - Sian Ellard
- Department of Molecular Genetics, Royal Devon & Exeter NHS Foundation Trust, Exeter, United Kingdom
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, United Kingdom
| | - Detlef Bockenhauer
- UCL Department of Renal Medicine, London, United Kingdom
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
- Correspondence: Detlef Bockenhauer, UCL Department of Renal Medicine, London WC1N 3JH, United Kingdom.
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24
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Kong Y, Xu K, Yuan K, Zhu J, Gu W, Liang L, Wang C. Digenetic inheritance of SLC12A3 and CLCNKB genes in a Chinese girl with Gitelman syndrome. BMC Pediatr 2019; 19:114. [PMID: 30999883 PMCID: PMC6471809 DOI: 10.1186/s12887-019-1498-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 04/09/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Gitelman syndrome (GS) is an autosomal recessive disorder and mild variant of classic Bartter syndrome. The latter is caused by defects in the genes CLCNKB and/or CLCNKA (chloride voltage-gated channel Ka and Kb). Patients with GS usually have loss-of-function mutations in SLC12A3. No patient has been reported with compound heterozygous mutations in these genes. We report a girl with GS with a paternally inherited heterozygous mutation in SLC12A3, and maternally inherited heterozygous variants in both CLCNKB and CLCNKA. CASE PRESENTATION In this report, we reported a female patient (8 y and 10 mo) who had growth retardation (111.8 cm, - 1.62 standard deviation height for age) and normal blood pressure, with persistent hypokalemia, hypomagnesemia, hypocalciuria, hypochloremic alkalosis, and elevated levels of plasma renin and aldosterone. Her younger brother, father, and paternal grandmother all had histories of mild low levels of plasma potassium (3.0-3.5 mmol/L), which were rectified by potassium-rich foods. The genomic DNA of the patient, younger brother, parents, and grandparents were screened for gene variations and pedigree analysis using trio whole exome sequencing (WES). The candidate variants were validated by Sanger sequencing. Protein-protein interaction analysis utilized the following databases: Biogrid, MINT, HPRD, STRING, IntAct, iRefIndex, and ppiTrim. The trio WES screening showed that the patient has paternally inherited SLC12A3 p.N359K, and maternally inherited CLCNKB p.L94I. The paternal grandmother and younger brother are both carriers of SLC12A3 p.N359K. According to the STRING database, SLC12A3 and CLCNKB proteins may interact or coexpress with proteins associated with GS. CONCLUSIONS Based on clinical phenotypes, genetic evidence of the pedigree, and previous reported studies, this case of GS indicates a digenetic inheritance of SLC12A3 and CLCNKB that resulted in renal tubular dysfunction perhaps, due to a genetic double-hit mechanism. The putative pathogenicity of the CLCNKB p.L94I variant requires confirmation.
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Affiliation(s)
- Yuanmei Kong
- The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Ke Xu
- Chigene Translational Medicine Research Center, Beijing, China
| | - Ke Yuan
- The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Jianfang Zhu
- The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Weiyue Gu
- Chigene Translational Medicine Research Center, Beijing, China
| | - Li Liang
- The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Chunlin Wang
- The First Affiliated Hospital of Zhejiang University, Hangzhou, China.
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wang C, Chen Y, Zheng B, Zhu M, Fan J, Wang J, Jia Z, Huang S, Zhang A. Novel compound heterozygous CLCNKB gene mutations (c.1755A>G/c.848_850delTCT) cause classic Bartter syndrome. Am J Physiol Renal Physiol 2018; 315:F844-F851. [PMID: 29442545 DOI: 10.1152/ajprenal.00077.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inactivated variants in CLCNKB gene encoding the basolateral chloride channel ClC-Kb cause classic Bartter syndrome characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here, we identified two cBS siblings presenting hypokalemia in a Chinese family due to novel compound heterozygous CLCNKB mutations (c.848_850delTCT/c.1755A>G). Compound heterozygosity was confirmed by amplifying and sequencing the patient's genomic DNA. The synonymous mutation c.1755A>G (Thr585Thr) was located at +2 bp from the 5' splice donor site in exon 15. Further transcript analysis demonstrated that this single nucleotide mutation causes exclusion of exon 15 in the cDNA from the proband and his mother. Furthermore, we investigated the expression and protein trafficking change of c.848_850delTCT (ΔTCT) and exon 15 deletion (ΔE15) mutation in vitro. The ΔE15 mutation markedly decreased the expression of ClC-Kb and resulted in a low-molecular-weight band (~55 kDa) trapping in the endoplasmic reticulum, while the ΔTCT mutant only decreased the total and plasma membrane ClC-Kb protein expression but did not affect the subcellular localization. Finally, we studied the physiological functions of mutations by using whole cell patch-clamp and found that the ΔE15 or ΔTCT mutation decreased the current of the ClC-Kb/barttin channel. These results suggested that the compound defective mutations of the CLCNKB gene are the molecular mechanism of the two cBS siblings.
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Affiliation(s)
- Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Ying Chen
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Mengshu Zhu
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Jia Fan
- Department of Physiology, Nanjing Medical University , Nanjing , China
| | - Juejin Wang
- Department of Physiology, Nanjing Medical University , Nanjing , China
| | - Zhanjun Jia
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Songming Huang
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University , Nanjing , China
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University , Nanjing , China
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Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
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Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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Abstract
PURPOSE OF REVIEW Antenatal Bartter syndrome (aBS) is a heterogenous disease resulting from defective ion transport in the thick ascending limb of the loop of Henle. Novel insights into the pathophysiology, as well as the recent identification of a novel genetic cause of aBS, merit an update on this topic. RECENT FINDINGS In aBS, severe salt losing is further aggravated by defective salt sensing in the macula densa, where a reduced tubular salt concentration is perceived and glomerular filtration is increased instead of decreased. As patients with aBS come of age, there is an increased incidence of proteinuria and impaired renal function.Moreover, we recently reported a new form of aBS. Indeed, we described a series of nine families in whom pregnancies with male fetuses where complicated by acute polyhydramnios, preterm delivery and with severe but transient polyuria. We identified mutations in melanoma-associated antigen D2 in all study participants and showed, in vivo and in vitro, reduced expression of the furosemide and thiazide sensitive transporters sodium-potassium-2-chloride cotransporter and sodium chloride cotransporter, respectively. SUMMARY Genetic studies revealed the complexity of ion transport in the thick ascending limb of the loop of Henle and will help to clarify the pathophysiology, which is essential to design new therapies.
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Kleta R, Bockenhauer D. Salt-Losing Tubulopathies in Children: What's New, What's Controversial? J Am Soc Nephrol 2018; 29:727-739. [PMID: 29237739 PMCID: PMC5827598 DOI: 10.1681/asn.2017060600] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Renal tubulopathies provide insights into the inner workings of the kidney, yet also pose therapeutic challenges. Because of the central nature of sodium in tubular transport physiology, disorders of sodium handling may affect virtually all aspects of the homeostatic functions of the kidney. Yet, owing to the rarity of these disorders, little clinical evidence regarding treatment exists. Consequently, treatment can vary widely between individual physicians and centers and is based mainly on understanding of renal physiology, reported clinical observations, and individual experiences. Salt-losing tubulopathies can affect all tubular segments, from the proximal tubule to the collecting duct. But the more frequently observed disorders are Bartter and Gitelman syndrome, which affect salt transport in the thick ascending limb of Henle's loop and/or the distal convoluted tubule, and these disorders generate the greatest controversies regarding management. Here, we review clinical and molecular aspects of salt-losing tubulopathies and discuss novel insights provided mainly by genetic investigations and retrospective clinical reviews. Additionally, we discuss controversial topics in the management of these disorders to highlight areas of importance for future clinical trials. International collaboration will be required to perform clinical studies to inform the treatment of these rare disorders.
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Affiliation(s)
- Robert Kleta
- UCL Centre for Nephrology and Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom
| | - Detlef Bockenhauer
- UCL Centre for Nephrology and Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom
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Ashton EJ, Legrand A, Benoit V, Roncelin I, Venisse A, Zennaro MC, Jeunemaitre X, Iancu D, Van't Hoff WG, Walsh SB, Godefroid N, Rotthier A, Del Favero J, Devuyst O, Schaefer F, Jenkins LA, Kleta R, Dahan K, Vargas-Poussou R, Bockenhauer D. Simultaneous sequencing of 37 genes identified causative mutations in the majority of children with renal tubulopathies. Kidney Int 2018; 93:961-967. [PMID: 29398133 DOI: 10.1016/j.kint.2017.10.016] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Revised: 09/29/2017] [Accepted: 10/05/2017] [Indexed: 12/25/2022]
Abstract
The clinical diagnosis of inherited renal tubulopathies can be challenging as they are rare and characterized by significant phenotypic variability. Advances in sequencing technologies facilitate the establishment of a molecular diagnosis. Therefore, we determined the diagnostic yield of a next generation sequencing panel assessing relevant disease genes in children followed through three national networks with a clinical diagnosis of a renal tubulopathy. DNA was amplified with a kit provided by the European Consortium for High-Throughput Research in Rare Kidney Diseases with nine multiplex PCR reactions. This kit produced 571 amplicons covering 37 genes associated with tubulopathies followed by massive parallel sequencing and bioinformatic interpretation. Identified mutations were confirmed by Sanger sequencing. Overall, 384 index patients and 16 siblings were assessed. Most common clinical diagnoses were 174 patients with Bartter/Gitelman syndrome and 76 with distal renal tubular acidosis. A total of 269 different variants were identified in 27 genes, of which 95 variants were considered likely, 136 definitely pathogenic and 100 had not been described at annotation. These mutations established a genetic diagnosis in 245 of the index patients. Genetic testing changed the clinical diagnosis in 16 cases and provided insights into the phenotypic spectrum of the respective disorders. Our results demonstrate a high diagnostic yield of genetic testing in children with a clinical diagnosis of a renal tubulopathy, consistent with a predominantly genetic etiology in known disease genes. Thus, genetic testing helped establish a definitive diagnosis in almost two-thirds of patients thereby informing prognosis, management and genetic counseling.
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Affiliation(s)
- Emma J Ashton
- North East Thames Regional Genetics Service Laboratories, Great Ormond Street Hospital for Children National Health Service (NHS) Foundation Trust, London, UK
| | - Anne Legrand
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France; Faculty of Medicine, Paris Sorbonne Cité, Université Paris Descartes, Paris, France
| | - Valerie Benoit
- Center of Human Genetics, Institut de Pathologie et Génétique, Gosselies, Belgium
| | - Isabelle Roncelin
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Annabelle Venisse
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Maria-Christina Zennaro
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France; Faculty of Medicine, Paris Sorbonne Cité, Université Paris Descartes, Paris, France; Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
| | - Xavier Jeunemaitre
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France; Faculty of Medicine, Paris Sorbonne Cité, Université Paris Descartes, Paris, France; Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
| | - Daniela Iancu
- Centre for Nephrology, University College London, London, UK
| | - William G Van't Hoff
- Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK
| | - Nathalie Godefroid
- Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium
| | | | | | - Olivier Devuyst
- Institute of Physiology, Zurich Center for Integrative Human Physiology, Mechanisms of Inherited Kidney Disorders Group, University of Zurich, Zurich, Switzerland; Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium
| | - Franz Schaefer
- Division of Paediatric Nephrology, Heidelberg University Center for Pediatrics and Adolescent Medicine, Heidelberg, Germany
| | - Lucy A Jenkins
- North East Thames Regional Genetics Service Laboratories, Great Ormond Street Hospital for Children National Health Service (NHS) Foundation Trust, London, UK
| | - Robert Kleta
- Centre for Nephrology, University College London, London, UK; Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Karin Dahan
- Center of Human Genetics, Institut de Pathologie et Génétique, Gosselies, Belgium; Division of Nephrology, Université Catholique de Louvain Medical School, Brussels, Belgium
| | - Rosa Vargas-Poussou
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France; Faculty of Medicine, Paris Sorbonne Cité, Université Paris Descartes, Paris, France.
| | - Detlef Bockenhauer
- Centre for Nephrology, University College London, London, UK; Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
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Blanchard A, Bockenhauer D, Bolignano D, Calò LA, Cosyns E, Devuyst O, Ellison DH, Karet Frankl FE, Knoers NVAM, Konrad M, Lin SH, Vargas-Poussou R. Gitelman syndrome: consensus and guidance from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference. Kidney Int 2017; 91:24-33. [PMID: 28003083 DOI: 10.1016/j.kint.2016.09.046] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/14/2016] [Accepted: 09/28/2016] [Indexed: 12/18/2022]
Abstract
Gitelman syndrome (GS) is a rare, salt-losing tubulopathy characterized by hypokalemic metabolic alkalosis with hypomagnesemia and hypocalciuria. The disease is recessively inherited, caused by inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive sodium-chloride cotransporter (NCC). GS is usually detected during adolescence or adulthood, either fortuitously or in association with mild or nonspecific symptoms or both. The disease is characterized by high phenotypic variability and a significant reduction in the quality of life, and it may be associated with severe manifestations. GS is usually managed by a liberal salt intake together with oral magnesium and potassium supplements. A general problem in rare diseases is the lack of high quality evidence to inform diagnosis, prognosis, and management. We report here on the current state of knowledge related to the diagnostic evaluation, follow-up, management, and treatment of GS; identify knowledge gaps; and propose a research agenda to substantiate a number of issues related to GS. This expert consensus statement aims to establish an initial framework to enable clinical auditing and thus improve quality control of care.
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Affiliation(s)
- Anne Blanchard
- Faculté de Médecine, Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Centre d'Investigation Clinique, Paris, France; Centre d'Investigation Clinique 1418, Institut National de la Santé et de la Recherche Médicale, Paris, France; UMR 970, Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Detlef Bockenhauer
- Centre for Nephrology, University College London, London, UK; Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, UK
| | - Davide Bolignano
- Institute of Clinical Physiology, National Research Council, Reggio, Calabria, Italy
| | - Lorenzo A Calò
- Department of Medicine, Nephrology, University of Padova, Padova, Italy
| | | | - Olivier Devuyst
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
| | - David H Ellison
- Division of Nephrology and Hypertension, Oregon Health and Science University, Veterans Affairs Portland Health Care System, Portland, Oregon, USA
| | - Fiona E Karet Frankl
- Department of Medical Genetics, University of Cambridge and Cambridge University Hospitals National Health Service Trust, Cambridge, UK; Division of Renal Medicine, University of Cambridge and Cambridge University Hospitals National Health Service Trust, Cambridge, UK
| | - Nine V A M Knoers
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Rosa Vargas-Poussou
- Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Centre d'Investigation Clinique, Paris, France; Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
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Viering DHHM, de Baaij JHF, Walsh SB, Kleta R, Bockenhauer D. Genetic causes of hypomagnesemia, a clinical overview. Pediatr Nephrol 2017; 32:1123-1135. [PMID: 27234911 PMCID: PMC5440500 DOI: 10.1007/s00467-016-3416-3] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 12/16/2022]
Abstract
Magnesium is essential to the proper functioning of numerous cellular processes. Magnesium ion (Mg2+) deficits, as reflected in hypomagnesemia, can cause neuromuscular irritability, seizures and cardiac arrhythmias. With normal Mg2+ intake, homeostasis is maintained primarily through the regulated reabsorption of Mg2+ by the thick ascending limb of Henle's loop and distal convoluted tubule of the kidney. Inadequate reabsorption results in renal Mg2+ wasting, as evidenced by an inappropriately high fractional Mg2+ excretion. Familial renal Mg2+ wasting is suggestive of a genetic cause, and subsequent studies in these hypomagnesemic families have revealed over a dozen genes directly or indirectly involved in Mg2+ transport. Those can be classified into four groups: hypercalciuric hypomagnesemias (encompassing mutations in CLDN16, CLDN19, CASR, CLCNKB), Gitelman-like hypomagnesemias (CLCNKB, SLC12A3, BSND, KCNJ10, FYXD2, HNF1B, PCBD1), mitochondrial hypomagnesemias (SARS2, MT-TI, Kearns-Sayre syndrome) and other hypomagnesemias (TRPM6, CNMM2, EGF, EGFR, KCNA1, FAM111A). Although identification of these genes has not yet changed treatment, which remains Mg2+ supplementation, it has contributed enormously to our understanding of Mg2+ transport and renal function. In this review, we discuss general mechanisms and symptoms of genetic causes of hypomagnesemia as well as the specific molecular mechanisms and clinical phenotypes associated with each syndrome.
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Affiliation(s)
- Daan H H M Viering
- Centre for Nephrology, University College London, London, UK
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK
| | - Robert Kleta
- Centre for Nephrology, University College London, London, UK.
- Paediatric Nephrology, Great Ormond Street Hospital, London, UK.
| | - Detlef Bockenhauer
- Centre for Nephrology, University College London, London, UK
- Paediatric Nephrology, Great Ormond Street Hospital, London, UK
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Hofmeister AF, Kömhoff M, Weber S, Grgic I. Disease modeling in genetic kidney diseases: mice. Cell Tissue Res 2017; 369:159-170. [PMID: 28601904 DOI: 10.1007/s00441-017-2639-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 05/04/2017] [Indexed: 12/27/2022]
Abstract
The mouse still represents arguably the most important mammal organism in research for modeling human genetic kidney diseases in vivo. Compared with many other mammal species, the breeding and maintenance of mice in the laboratory is relatively simple and cheap and reproduction cycles are short. In addition to classic gene knockout mouse lines, new molecular biological technologies have led to the development of a plethora of other, more sophisticated, mouse models, allowing the targeting of genes or gene function in a cell-specific, tissue-specific and time-dependent fashion. With the refinement of more recently developed genome-editing technologies, including the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system and other engineered nucleases such as zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), our "tool set" of mouse models is expected to rapidly expand. These technological advances hold great promise and should enable us to study and hence understand the biology of inherited kidney diseases in greater detail. By analogy, we may be able to answer questions regarding the impact of individual proteins on the development of human kidney disorders, the underlying mechanisms governing the evolution of the disease and the predicted responsiveness to therapeutic interventions. Moreover, knockout and transgenic mouse models can be highly informative with respect to the effects of genetic variations on renal phenotypes. This review focuses on mouse models that have been devised primarily to study monogenic human kidney diseases, which are typically caused by a single abnormal gene and passed on in a Mendelian pattern. Despite the large number of human hereditary kidney disorders and the multitude of mouse models described in the literature, we attempt to give a balanced overview of several well-known renal pathologies, a few of which are addressed in some detail.
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Affiliation(s)
- Andreas F Hofmeister
- Department of Internal Medicine and Nephrology, University Hospital Giessen and Marburg, Philipps-University Marburg, Baldingerstrasse 1, 35033, Marburg, Germany
| | - Martin Kömhoff
- University Children's Hospital, Philipps-University Marburg, Marburg, Germany
| | - Stefanie Weber
- University Children's Hospital, Philipps-University Marburg, Marburg, Germany
| | - Ivica Grgic
- Department of Internal Medicine and Nephrology, University Hospital Giessen and Marburg, Philipps-University Marburg, Baldingerstrasse 1, 35033, Marburg, Germany.
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Subasinghe CJ, Sirisena ND, Herath C, Berge KE, Leren TP, Bulugahapitiya U, Dissanayake VHW. Novel mutation in the SLC12A3 gene in a Sri Lankan family with Gitelman syndrome & coexistent diabetes: a case report. BMC Nephrol 2017; 18:140. [PMID: 28446151 PMCID: PMC5406964 DOI: 10.1186/s12882-017-0563-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 04/20/2017] [Indexed: 12/11/2022] Open
Abstract
Background Gitelman syndrome (GS) is a rare autosomal recessively inherited salt-wasting tubulopathy associated with mutations in the SLC12A3 gene, which encodes for NaCl cotransporter (NCC) in the kidney. Case presentation In this report, we describe two siblings from a Sri Lankan non-consanguineous family presenting with hypokalaemia associated with renal potassium wasting, hypomagnesemia, hypocalciuria and hypereninemic hyperaldosteronism with normal blood pressure. Genetic testing showed that both were homozygotes for a novel missense mutation in exon 10 of the SLC12A3 gene [NM_000339.2, c.1276A > T; p.N426Y], which has not previously been reported in the literature in association with GS. Their mother was a heterozygous carrier for the same mutation. The father was not alive at the time of testing. This novel mutation extends the spectrum of known SLC12A3 gene mutations and further supports the allelic heterogeneity of GS. Interestingly both siblings had young onset Diabetes with strong family history. Conclusion These findings have implications in providing appropriate genetic counseling to the family with regard to the risk associated with inbreeding, the detection of carrier/presymptomatic relatives. It further expands the known spectrum of genotypic and phenotypic characteristics of Gitelman syndrome.
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Affiliation(s)
| | | | - Chula Herath
- Nephrology Unit, Sri Jayewardenepura General Hospital, Thalapathpitiya, Nugegoda, Sri Lanka
| | - Knut Erik Berge
- Unit for Cardiac and Cardiovascular Genetics, Department for Medical Genetics, Oslo University Hospital, Ullevaal, Oslo, Norway
| | - Trond Paul Leren
- Unit for Cardiac and Cardiovascular Genetics, Department for Medical Genetics, Oslo University Hospital, Ullevaal, Oslo, Norway
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Seys E, Andrini O, Keck M, Mansour-Hendili L, Courand PY, Simian C, Deschenes G, Kwon T, Bertholet-Thomas A, Bobrie G, Borde JS, Bourdat-Michel G, Decramer S, Cailliez M, Krug P, Cozette P, Delbet JD, Dubourg L, Chaveau D, Fila M, Jourde-Chiche N, Knebelmann B, Lavocat MP, Lemoine S, Djeddi D, Llanas B, Louillet F, Merieau E, Mileva M, Mota-Vieira L, Mousson C, Nobili F, Novo R, Roussey-Kesler G, Vrillon I, Walsh SB, Teulon J, Blanchard A, Vargas-Poussou R. Clinical and Genetic Spectrum of Bartter Syndrome Type 3. J Am Soc Nephrol 2017; 28:2540-2552. [PMID: 28381550 DOI: 10.1681/asn.2016101057] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/27/2017] [Indexed: 12/30/2022] Open
Abstract
Bartter syndrome type 3 is a clinically heterogeneous hereditary salt-losing tubulopathy caused by mutations of the chloride voltage-gated channel Kb gene (CLCNKB), which encodes the ClC-Kb chloride channel involved in NaCl reabsorption in the renal tubule. To study phenotype/genotype correlations, we performed genetic analyses by direct sequencing and multiplex ligation-dependent probe amplification and retrospectively analyzed medical charts for 115 patients with CLCNKB mutations. Functional analyses were performed in Xenopus laevis oocytes for eight missense and two nonsense mutations. We detected 60 mutations, including 27 previously unreported mutations. Among patients, 29.5% had a phenotype of ante/neonatal Bartter syndrome (polyhydramnios or diagnosis in the first month of life), 44.5% had classic Bartter syndrome (diagnosis during childhood, hypercalciuria, and/or polyuria), and 26.0% had Gitelman-like syndrome (fortuitous discovery of hypokalemia with hypomagnesemia and/or hypocalciuria in childhood or adulthood). Nine of the ten mutations expressed in vitro decreased or abolished chloride conductance. Severe (large deletions, frameshift, nonsense, and essential splicing) and missense mutations resulting in poor residual conductance were associated with younger age at diagnosis. Electrolyte supplements and indomethacin were used frequently to induce catch-up growth, with few adverse effects. After a median follow-up of 8 (range, 1-41) years in 77 patients, chronic renal failure was detected in 19 patients (25%): one required hemodialysis and four underwent renal transplant. In summary, we report a genotype/phenotype correlation for Bartter syndrome type 3: complete loss-of-function mutations associated with younger age at diagnosis, and CKD was observed in all phenotypes.
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Affiliation(s)
- Elsa Seys
- Pediatric Nephrology Unit, American Memorial Hospital, Reims University Hospital, Reims, France
| | - Olga Andrini
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Faculté de Médecine, Université Paris Descartes, Paris, France
| | - Mathilde Keck
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 872, Paris, France
| | | | - Pierre-Yves Courand
- Centre d'Investigation Clinique, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France.,Cardiology Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France.,Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé; Centre National de la Recherche Scientifique Unité Mixte de Recherche 5220; Institut National de la Santé et la Recherche Médicale, Unité 1044; Institut National de Sciences Appliquées-Lyon; Université Claude Bernard Lyon 1, France
| | | | - Georges Deschenes
- Pediatric Nephrology Unit, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
| | - Theresa Kwon
- Pediatric Nephrology Unit, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
| | - Aurélia Bertholet-Thomas
- Néphrogones, Centre de Référence des Maladies Rénales Rares, Pediatric Nephrology, Rhumatology and Dermatology Unit, Hôpital Femme-Mère-Enfant and
| | - Guillaume Bobrie
- Nephrology Unit, Clinique du Vert Galant, Tremblay-en-France, France
| | | | | | | | - Mathilde Cailliez
- Pediatric Nephrology Unit, Hôpital de la Timone, Assistance Publique des Hôpitaux de Marseille, Marseille, France
| | - Pauline Krug
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Pediatric Nephrology Unit and
| | - Paul Cozette
- Nephrology Unit, Centre Hospitalier du Pays d'Aix, Aix-en-Provence, France
| | - Jean Daniel Delbet
- Pediatric Nephrology Unit, Hôpital Trousseau, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - Laurence Dubourg
- Exploration Fonctionnelle Rénale et Métabolique, Groupement Hospitalier est Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France
| | - Dominique Chaveau
- Departement of Nephrology, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Hôpital de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Marc Fila
- Pediatric Nephrology Unit, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
| | - Noémie Jourde-Chiche
- Faculté de Médecine, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Aix-MarseilleUniversité-Vascular Research Center of Marseille, Marseille, France.,Nephrology Unit, Hôpital de la Conception, Assistance Publique des Hopitaux de Marseille, Marseille,France
| | - Bertrand Knebelmann
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Department of Nephrology, Hôpital Necker-Enfants-malades, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - Marie-Pierre Lavocat
- Departement of Pediatrics, Hôpital Nord, Centre Hospitalier Universitaire de Saint Etienne, Saint Etienne, France
| | - Sandrine Lemoine
- Exploration Fonctionnelle Rénale et Métabolique, Groupement Hospitalier est Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France
| | - Djamal Djeddi
- Department of Pediatrics and Adolescent Medicine, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - Brigitte Llanas
- Service de Néphrologie Pédiatrique, Groupement Hospitalier Pellegrin, Centre Hospitalier Universitaire de Bordeaux, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Bordeaux, France
| | - Ferielle Louillet
- Department of Pediatrics, Centre Hospitalier Universitaire Charles Nicolle, Rouen, France
| | - Elodie Merieau
- Nephrology Unit,Centre Hospitalier Universitaire Tours, Tours, France
| | - Maria Mileva
- Department of Pediatrics, Centre Hospitalier Pierre Oudot de Bourgoin-Jallieu, Bourgoin-Jallieu, France
| | - Luisa Mota-Vieira
- Molecular Genetics Unit, Hospital do Divino Espírito Santo de Ponta Delgada, Entidade Pública Empresarial Regional, Açores, Portugal
| | - Christiane Mousson
- Nephrology Unit, Centre Hospitalier Universitaire de Dijon, Dijon, France
| | - François Nobili
- Pediatric Nephrology Unit, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Robert Novo
- Pediatric Nephrology Unit, Hôpital Jeanne de Flandre, Centre Hospitalier Universitaire de Lille, Lille, France
| | | | - Isabelle Vrillon
- Pediatric Nephrology Unit, Hôpitaux de Brabois, Centre Hospitalier Universitaire de Nancy, Vandoeuvre Les Nancy, France
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK; and
| | - Jacques Teulon
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 872, Paris, France
| | - Anne Blanchard
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Cardiology Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
| | - Rosa Vargas-Poussou
- Department of Genetics and.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
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Abstract
PURPOSE OF REVIEW Magnesium (Mg) imbalances are frequently overlooked. Hypermagnesemia usually occurs in preeclamptic women after Mg therapy or in end-stage renal disease patients, whereas hypomagnesemia is more common with a prevalence of up to 15% in the general population. Increasing evidence points toward a role for mild-to-moderate chronic hypomagnesemia in the pathogenesis of hypertension, type 2 diabetes mellitus, and metabolic syndrome. RECENT FINDINGS The kidneys are the major regulator of total body Mg homeostasis. Over the last decade, the identification of the responsible genes in rare genetic disorders has enhanced our understanding of how the kidney handles Mg. The different genetic disorders and medications contributing to abnormal Mg homeostasis are reviewed. SUMMARY As dysfunctional Mg homeostasis contributes to the development of many common human disorders, serum Mg deserves closer monitoring. Hypomagnesemic patients may be asymptomatic or may have mild symptoms. In severe hypomagnesemia, patients may present with neurological symptoms such as seizures, spasms, or cramps. Renal symptoms include nephrocalcinosis and impaired renal function. Most conditions affect tubular Mg reabsorption by disturbing the lumen-positive potential in the thick ascending limb or the negative membrane potential in the distal convoluted tubule.
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García Castaño A, Pérez de Nanclares G, Madariaga L, Aguirre M, Madrid Á, Chocrón S, Nadal I, Navarro M, Lucas E, Fijo J, Espino M, Espitaletta Z, García Nieto V, Barajas de Frutos D, Loza R, Pintos G, Castaño L, Ariceta G. Poor phenotype-genotype association in a large series of patients with Type III Bartter syndrome. PLoS One 2017; 12:e0173581. [PMID: 28288174 PMCID: PMC5348002 DOI: 10.1371/journal.pone.0173581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 02/22/2017] [Indexed: 12/19/2022] Open
Abstract
Introduction Type III Bartter syndrome (BS) is an autosomal recessive renal tubule disorder caused by loss-of-function mutations in the CLCNKB gene, which encodes the chloride channel protein ClC-Kb. In this study, we carried out a complete clinical and genetic characterization in a cohort of 30 patients, one of the largest series described. By comparing with other published populations, and considering that 80% of our patients presented the p.Ala204Thr Spanish founder mutation presumably associated with a common phenotype, we aimed to test the hypothesis that allelic differences could explain the wide phenotypic variability observed in patients with type III BS. Methods Clinical data were retrieved from the referral centers. The exon regions and flanking intronic sequences of the CLCNKB gene were screened for mutations by polymerase chain reaction (PCR) followed by direct Sanger sequencing. Presence of gross deletions or duplications in the region was checked for by MLPA and QMPSF analyses. Results Polyuria, polydipsia and dehydration were the main common symptoms. Metabolic alkalosis and hypokalemia of renal origin were detected in all patients at diagnosis. Calciuria levels were variable: hypercalciuria was detected in 31% of patients, while 23% had hypocalciuria. Nephrocalcinosis was diagnosed in 20% of the cohort. Two novel CLCNKB mutations were identified: a small homozygous deletion (c.753delG) in one patient and a small deletion (c.1026delC) in another. The latter was present in compound heterozygosis with the already previously described p.Glu442Gly mutation. No phenotypic association was obtained regarding the genotype. Conclusion A poor correlation was found between a specific type of mutation in the CLCNKB gene and type III BS phenotype. Importantly, two CLCNKB mutations not previously described were found in our cohort.
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Affiliation(s)
| | | | - Leire Madariaga
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
| | - Mireia Aguirre
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
| | - Álvaro Madrid
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
| | - Sara Chocrón
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
| | - Inmaculada Nadal
- Pediatric Nephrology, Virgen del Camino Hospital, Pamplona, Spain
| | | | - Elena Lucas
- Pediatrics, Manises Hospital, Valencia, Spain
| | - Julia Fijo
- Pediatric Nephrology, Virgen del Rocío Hospital, Sevilla, Spain
| | - Mar Espino
- Pediatric Nephrology, Fundación Alcorcón University Hospital, Madrid, Spain
| | | | - Víctor García Nieto
- Pediatric Nephrology, Nuestra Señora de Candelaria University Hospital, Tenerife, Canarias, Spain
| | | | - Reyner Loza
- Nephrology Unit, Cayetano Heredia University, Cayetano Heredia Hospital, Lima, Peru
| | - Guillem Pintos
- Germans Trias i Pujol University Hospital, Badalona, Spain
| | - Luis Castaño
- BioCruces Health Research Institute, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - RenalTube Group
- BioCruces Health Research Institute, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
- Pediatric Nephrology, Nuestra Señora de Candelaria University Hospital, Tenerife, Canarias, Spain
- Pediatric Nephrology, Asturias Central University Hospital, Oviedo, Asturias, Spain
| | - Gema Ariceta
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
- * E-mail:
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38
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Liu Y, Rafferty TM, Rhee SW, Webber JS, Song L, Ko B, Hoover RS, He B, Mu S. CD8 + T cells stimulate Na-Cl co-transporter NCC in distal convoluted tubules leading to salt-sensitive hypertension. Nat Commun 2017; 8:14037. [PMID: 28067240 PMCID: PMC5227995 DOI: 10.1038/ncomms14037] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 11/23/2016] [Indexed: 12/12/2022] Open
Abstract
Recent studies suggest a role for T lymphocytes in hypertension. However, whether T cells contribute to renal sodium retention and salt-sensitive hypertension is unknown. Here we demonstrate that T cells infiltrate into the kidney of salt-sensitive hypertensive animals. In particular, CD8+ T cells directly contact the distal convoluted tubule (DCT) in the kidneys of DOCA-salt mice and CD8+ T cell-injected mice, leading to up-regulation of the Na-Cl co-transporter NCC, p-NCC and the development of salt-sensitive hypertension. Co-culture with CD8+ T cells upregulates NCC in mouse DCT cells via ROS-induced activation of Src kinase, up-regulation of the K+ channel Kir4.1, and stimulation of the Cl- channel ClC-K. The last event increases chloride efflux, leading to compensatory chloride influx via NCC activation at the cost of increasing sodium retention. Collectively, these findings provide a mechanism for adaptive immunity involvement in the kidney defect in sodium handling and the pathogenesis of salt-sensitive hypertension.
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Affiliation(s)
- Yunmeng Liu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Tonya M Rafferty
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Sung W Rhee
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Jessica S Webber
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Li Song
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Benjamin Ko
- Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA
| | - Robert S Hoover
- Department of Medicine, Division of Nephrology, Emory University, Atlanta, Georgia 30322, USA.,Research Service Atlanta, Veteran's Administration Medical Center, Decatur, Georgia 30033, USA
| | - Beixiang He
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.,Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Shengyu Mu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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Cho HW, Lee ST, Cho H, Cheong HI. A novel mutation of CLCNKB in a Korean patient of mixed phenotype of Bartter-Gitelman syndrome. KOREAN JOURNAL OF PEDIATRICS 2016; 59:S103-S106. [PMID: 28018459 PMCID: PMC5177689 DOI: 10.3345/kjp.2016.59.11.s103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/11/2016] [Accepted: 01/27/2016] [Indexed: 12/11/2022]
Abstract
Bartter syndrome (BS) is an inherited renal tubular disorder characterized by low or normal blood pressure, hypokalemic metabolic alkalosis, and hyperreninemic hyperaldosteronism. Type III BS is caused by loss-of-function mutations in CLCNKB encoding basolateral ClC-Kb. The clinical phenotype of patients with CLCNKB mutations has been known to be highly variable, and cases that are difficult to categorize as type III BS or other hereditary tubulopathies, such as Gitelman syndrome, have been rarely reported. We report a case of a 10-year-old Korean boy with atypical clinical findings caused by a novel CLCNKB mutation. The boy showed intermittent muscle cramps with laboratory findings of hypokalemia, severe hypomagnesemia, and nephrocalcinosis. These findings were not fully compatible with those observed in cases of BS or Gitelman syndrome. The CLCNKB mutation analysis revealed a heterozygous c.139G>A transition in exon 13 [p.Gly(GGG)465Glu(GAG)]. This change is not a known mutation; however, the clinical findings and in silico prediction results indicated that it is the underlying cause of his presentation.
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Affiliation(s)
- Hee-Won Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sang Taek Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
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40
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Grillone T, Menniti M, Bombardiere F, Vismara MFM, Belviso S, Fabiani F, Perrotti N, Iuliano R, Colao E. New SLC12A3 disease causative mutation of Gitelman’s syndrome. World J Nephrol 2016; 5:551-555. [PMID: 27872838 PMCID: PMC5099602 DOI: 10.5527/wjn.v5.i6.551] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/21/2016] [Accepted: 09/22/2016] [Indexed: 02/06/2023] Open
Abstract
Gitelman’s syndrome (GS) is a salt-losing tubulopathy with an autosomal recessive inheritance caused by mutations of SLC12A3, which encodes for the thiazide-sensitive NaCl cotransporter. In this study we report a new mutation of SLC12A3 found in two brothers affected by GS. Hypokalemia, hypocalciuria and hyper-reninemia were present in both patients while hypomagnesemia was detected only in one. Both patients are compound heterozygotes carrying one well known GS associated mutation (c.2581 C > T) and a new one (c.283delC) in SLC12A3 gene. The new mutation results in a possible frame-shift with a premature stop-codon (pGln95ArgfsX19). The parents of the patients, heterozygous carriers of the mutations found in SLC12A3, have no disease associated phenotype. Therefore, the new mutation is causative of GS.
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Hennings JC, Andrini O, Picard N, Paulais M, Huebner AK, Cayuqueo IKL, Bignon Y, Keck M, Cornière N, Böhm D, Jentsch TJ, Chambrey R, Teulon J, Hübner CA, Eladari D. The ClC-K2 Chloride Channel Is Critical for Salt Handling in the Distal Nephron. J Am Soc Nephrol 2016; 28:209-217. [PMID: 27335120 DOI: 10.1681/asn.2016010085] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/04/2016] [Indexed: 11/03/2022] Open
Abstract
Chloride transport by the renal tubule is critical for blood pressure (BP), acid-base, and potassium homeostasis. Chloride uptake from the urinary fluid is mediated by various apical transporters, whereas basolateral chloride exit is thought to be mediated by ClC-Ka/K1 and ClC-Kb/K2, two chloride channels from the ClC family, or by KCl cotransporters from the SLC12 gene family. Nevertheless, the localization and role of ClC-K channels is not fully resolved. Because inactivating mutations in ClC-Kb/K2 cause Bartter syndrome, a disease that mimics the effects of the loop diuretic furosemide, ClC-Kb/K2 is assumed to have a critical role in salt handling by the thick ascending limb. To dissect the role of this channel in detail, we generated a mouse model with a targeted disruption of the murine ortholog ClC-K2. Mutant mice developed a Bartter syndrome phenotype, characterized by renal salt loss, marked hypokalemia, and metabolic alkalosis. Patch-clamp analysis of tubules isolated from knockout (KO) mice suggested that ClC-K2 is the main basolateral chloride channel in the thick ascending limb and in the aldosterone-sensitive distal nephron. Accordingly, ClC-K2 KO mice did not exhibit the natriuretic response to furosemide and exhibited a severely blunted response to thiazide. We conclude that ClC-Kb/K2 is critical for salt absorption not only by the thick ascending limb, but also by the distal convoluted tubule.
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Affiliation(s)
- J Christopher Hennings
- Institut für Humangenetik, University Hospital Jena, Friedrich-Schiller-Universität, Jena, Germany
| | - Olga Andrini
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Nicolas Picard
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Marc Paulais
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Antje K Huebner
- Institut für Humangenetik, University Hospital Jena, Friedrich-Schiller-Universität, Jena, Germany
| | - Irma Karen Lopez Cayuqueo
- Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris, France.,Centro de Estudios Científicos, Valdivia, Chile
| | - Yohan Bignon
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Mathilde Keck
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Nicolas Cornière
- Service de Néphrologie, Hôpital Felix Guyon, Centre Hospitalier Universitaire de la Réunion, St Denis, Ile de la Réunion, France
| | - David Böhm
- Institut für Humangenetik, University Hospital Jena, Friedrich-Schiller-Universität, Jena, Germany
| | - Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie and Max-Delbrück Centrum für Molekulare Medizin, Berlin, Germany
| | - Régine Chambrey
- Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris, France.,Faculté de Médecine, Université Paris-Descartes, Paris, France.,Centre National de la Recherche Scientifique, Paris, France; and
| | - Jacques Teulon
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche en Santé 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France;
| | - Christian A Hübner
- Institut für Humangenetik, University Hospital Jena, Friedrich-Schiller-Universität, Jena, Germany
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris, France; .,Faculté de Médecine, Université Paris-Descartes, Paris, France.,Département de Physiologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France
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Zaika O, Tomilin V, Mamenko M, Bhalla V, Pochynyuk O. New perspective of ClC-Kb/2 Cl- channel physiology in the distal renal tubule. Am J Physiol Renal Physiol 2016; 310:F923-30. [PMID: 26792067 PMCID: PMC5002062 DOI: 10.1152/ajprenal.00577.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/14/2016] [Indexed: 12/17/2022] Open
Abstract
Since its identification as the underlying molecular cause of Bartter's syndrome type 3, ClC-Kb (ClC-K2 in rodents, henceforth it will be referred as ClC-Kb/2) is proposed to play an important role in systemic electrolyte balance and blood pressure regulation by controlling basolateral Cl(-) exit in the distal renal tubular segments from the cortical thick ascending limb to the outer medullary collecting duct. Considerable experimental and clinical effort has been devoted to the identification and characterization of disease-causing mutations as well as control of the channel by its cofactor, barttin. However, we have only begun to unravel the role of ClC-Kb/2 in different tubular segments and to reveal the regulators of its expression and function, e.g., insulin and IGF-1. In this review we discuss recent experimental evidence in this regard and highlight unexplored questions critical to understanding ClC-Kb/2 physiology in the kidney.
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Affiliation(s)
- Oleg Zaika
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Mykola Mamenko
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Vivek Bhalla
- Division of Nephrology, Department of Medicine, Stanford University, Stanford, California
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
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Lee JW, Lee J, Heo NJ, Cheong HI, Han JS. Mutations in SLC12A3 and CLCNKB and Their Correlation with Clinical Phenotype in Patients with Gitelman and Gitelman-like Syndrome. J Korean Med Sci 2016; 31:47-54. [PMID: 26770037 PMCID: PMC4712579 DOI: 10.3346/jkms.2016.31.1.47] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 09/24/2015] [Indexed: 12/17/2022] Open
Abstract
Gitelman's syndrome (GS) is caused by loss-of-function mutations in SLC12A3 and characterized by hypokalemic metabolic alkalosis, hypocalciuria, and hypomagnesemia. Long-term prognosis and the role of gene diagnosis in GS are still unclear. To investigate genotype-phenotype correlation in GS and Gitelman-like syndrome, we enrolled 34 patients who showed hypokalemic metabolic alkalosis without secondary causes. Mutation analysis of SLC12A3 and CLCNKB was performed. Thirty-one patients had mutations in SLC12A3, 5 patients in CLCNKB, and 2 patients in both genes. There was no significant difference between male and female in clinical manifestations at the time of presentation, except for early onset of symptoms in males and more profound hypokalemia in females. We identified 10 novel mutations in SLC12A3 and 4 in CLCNKB. Compared with those with CLCNKB mutations, patients with SLC12A3 mutations were characterized by more consistent hypocalciuria and hypomagnesemia. Patients with 2 mutant SLC12A3 alleles, compared with those with 1 mutant allele, did not have more severe clinical and laboratory findings except for lower plasma magnesium concentrations. Male and female patients did not differ in their requirement for electrolyte replacements. Two patients with concomitant SLC12A3 and CLCNKB mutations had early-onset severe symptoms and showed different response to treatment. Hypocalciuria and hypomagnesemia are useful markers in differentiation of GS and classical Bartter's syndrome. Gender, genotypes or the number of SLC12A3 mutant alleles cannot predict the severity of disease or response to treatment.
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Affiliation(s)
- Jae Wook Lee
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
| | - Jeonghwan Lee
- Department of Internal Medicine, Hallym University Hangang Sacred Heart Hospital, Seoul, Korea
| | - Nam Ju Heo
- Department of Internal Medicine, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
- Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea
- Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea
| | - Jin Suk Han
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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Gattineni J, Baum M. Developmental changes in renal tubular transport-an overview. Pediatr Nephrol 2015; 30:2085-98. [PMID: 24253590 PMCID: PMC4028442 DOI: 10.1007/s00467-013-2666-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/01/2013] [Accepted: 10/11/2013] [Indexed: 10/26/2022]
Abstract
The adult kidney maintains a constant volume and composition of extracellular fluid despite changes in water and salt intake. The neonate is born with a kidney that has a small fraction of the glomerular filtration rate of the adult and immature tubules that function at a lower capacity than that of the mature animal. Nonetheless, the neonate is also able to maintain a constant extracellular fluid volume and composition. Postnatal renal tubular development was once thought to be due to an increase in the transporter abundance to meet the developmental increase in glomerular filtration rate. However, postnatal renal development of each nephron segment is quite complex. There are isoform changes of several transporters as well as developmental changes in signal transduction that affect the capacity of renal tubules to reabsorb solutes and water. This review will discuss neonatal tubular function with an emphasis on the differences that have been found between the neonate and adult. We will also discuss some of the factors that are responsible for the maturational changes in tubular transport that occur during postnatal renal development.
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Affiliation(s)
- Jyothsna Gattineni
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390-9061, USA
| | - Michel Baum
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390-9061, USA.
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Shibli AA, Narchi H. Bartter and Gitelman syndromes: Spectrum of clinical manifestations caused by different mutations. World J Methodol 2015; 5:55-61. [PMID: 26140272 PMCID: PMC4482822 DOI: 10.5662/wjm.v5.i2.55] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 05/14/2015] [Accepted: 06/08/2015] [Indexed: 02/06/2023] Open
Abstract
Bartter and Gitelman syndromes (BS and GS) are inherited disorders resulting in defects in renal tubular handling of sodium, potassium and chloride. Previously considered as genotypic and phenotypic heterogeneous diseases, recent evidence suggests that they constitute a spectrum of disease caused by different genetic mutations with the molecular defects of chloride reabsorption originating at different sites of the nephron in each condition. Although they share some characteristic metabolic abnormalities such as hypokalemia, metabolic alkalosis, hyperplasia of the juxtaglomerular apparatus with hyperreninemia, hyperaldosteronism, the clinical and laboratory manifestations may not always allow distinction between them. Diuretics tests, measuring the changes in urinary fractional excretion of chloride from baseline after administration of either hydrochlorothiazide or furosemide show very little change (< 2.3%) in the fractional excretion of chloride from baseline in GS when compared with BS, except when BS is associated with KCNJ1 mutations where a good response to both diuretics exists. The diuretic test is not recommended for infants or young children with suspected BS because of a higher risk of volume depletion in such children. Clinical symptoms and biochemical markers of GS and classic form of BS (type III) may overlap and thus genetic analysis may specify the real cause of symptoms. However, although genetic analysis is available, its use remains limited because of limited availability, large gene dimensions, lack of hot-spot mutations, heavy workup time and costs involved. Furthermore, considerable overlap exists between the different genotypes and phenotypes. Although BS and GS usually have distinct presentations and are associated with specific gene mutations, there remains considerable overlap between their phenotypes and genotypes. Thus, they are better described as a spectrum of clinical manifestations caused by different gene mutations.
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Andrini O, Keck M, Briones R, Lourdel S, Vargas-Poussou R, Teulon J. ClC-K chloride channels: emerging pathophysiology of Bartter syndrome type 3. Am J Physiol Renal Physiol 2015; 308:F1324-34. [DOI: 10.1152/ajprenal.00004.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/23/2015] [Indexed: 02/08/2023] Open
Abstract
The mutations in the CLCNKB gene encoding the ClC-Kb chloride channel are responsible for Bartter syndrome type 3, one of the four variants of Bartter syndrome in the genetically based nomenclature. All forms of Bartter syndrome are characterized by hypokalemia, metabolic alkalosis, and secondary hyperaldosteronism, but Bartter syndrome type 3 has the most heterogeneous presentation, extending from severe to very mild. A relatively large number of CLCNKB mutations have been reported, including gene deletions and nonsense or missense mutations. However, only 20 CLCNKB mutations have been functionally analyzed, due to technical difficulties regarding ClC-Kb functional expression in heterologous systems. This review provides an overview of recent progress in the functional consequences of CLCNKB mutations on ClC-Kb chloride channel activity. It has been observed that 1) all ClC-Kb mutants have an impaired expression at the membrane; and 2) a minority of the mutants combines reduced membrane expression with altered pH-dependent channel gating. Although further investigation is needed to fully characterize disease pathogenesis, Bartter syndrome type 3 probably belongs to the large family of conformational diseases, in which the mutations destabilize channel structure, inducing ClC-Kb retention in the endoplasmic reticulum and accelerated channel degradation.
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Affiliation(s)
- Olga Andrini
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Mathilde Keck
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rodolfo Briones
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stéphane Lourdel
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rosa Vargas-Poussou
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de Génétique, Paris, France; and
- Université Paris-Descartes, Faculté de Médecine, Paris, France
| | - Jacques Teulon
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
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Koulouridis E, Koulouridis I. Molecular pathophysiology of Bartter's and Gitelman's syndromes. World J Pediatr 2015; 11:113-25. [PMID: 25754753 DOI: 10.1007/s12519-015-0016-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 10/23/2014] [Indexed: 12/17/2022]
Abstract
BACKGROUND In the last two decades, progress in cytogenetic and genome research has enabled investigators to unravel the underlying molecular mechanisms of inherited tubulopathies such as Bartter's and Gitelman's syndromes and helped physicians to better understand not only these two pathologic entities but also renal pathophysiology and salt sensitive hypertension. DATA SOURCES Articles collected from PubMed and open access journals included original articles, research articles, and comprehensive reviews. They were evaluated by the authors with an special emphasis on originality and up to date information about molecular pathophysiology. RESULTS Bartter's and Gitelman's syndromes are two different inherited salt loosing tubulopathies. They are characterized by various inability of distal nephron to reabsorb sodium chloride with resultant extarcellular volume contraction and increased activity of the renin angiotensin aldosterone system. Hypokalemic metabolic alkalosis is a common feature of these two forms of tubulopathies. Hypercalciuria characterizes the majority of Bartter's syndrome, and hypomagnesemia with hypocalciuria characterizes Gitelman's syndrome. Low blood pressure is a common feature among patients who suffered from these tubulopathies. Bartter's syndromes encompass a heterogeneous group of ion channels defects localized at the thick ascending limp of Henle's loop with resultant loss of function of sodium-potassium-2 chloride cotransporter. These defects result in the impairment of the countercurrent multiplication system of the kidney as well as calcium, potassium and acid base disturbances which in the majority of cases are proved lethal especially in the antenatal and/or immediate postnatal life period. The underlying pathology in Gitelman's syndrome is defined to the distal convoluted tubule and is related to loss of function of the sodium-chloride cotransporter. The results of this defect encompass the inability of extracellular volume homeostasis, magnesium and potassium conservation, and acid base disturbances which are generally mild and in the majority of cases are not life-threatening. CONCLUSIONS Recent advances in molecular pathophysiology of Bartter's and Gitelman's syndromes have helped physicians to better understand the underlying mechanisms of these pathologic entities which remain obscure. Data collected from experiments among genetically manipulated animals enable us to better understand the pathophysiology of mammalian kidney and the underlying mechanisms of salt sensitive hypertension and to lay a foundation for the future development of new drugs, especially diuretics and antihypertensive drugs.
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de Baaij JHF, Hoenderop JGJ, Bindels RJM. Magnesium in man: implications for health and disease. Physiol Rev 2015; 95:1-46. [PMID: 25540137 DOI: 10.1152/physrev.00012.2014] [Citation(s) in RCA: 870] [Impact Index Per Article: 96.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Ohkubo K, Matsuzaki T, Yuki M, Yoshida R, Terawaki Y, Maeyama A, Kawashima H, Ono J, Yanase T, Matsunaga A. A novel mutation of CLCNKB in a Japanese patient of Gitelman-like phenotype with diuretic insensitivity to thiazide administration. Meta Gene 2014; 2:342-8. [PMID: 25606418 PMCID: PMC4287957 DOI: 10.1016/j.mgene.2014.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 04/09/2014] [Accepted: 04/10/2014] [Indexed: 11/28/2022] Open
Abstract
The clinical phenotypes of patients with Bartter syndrome type III sometimes closely resemble those of Gitelman syndrome. We report a patient with mild, adult-onset symptoms, such as muscular weakness and fatigue, who showed hypokalemic metabolic alkalosis, elevated renin–aldosterone levels with normal blood pressure, hypocalciuria and hypomagnesemia. She was also suffering from chondrocalcinosis. A diuretic test with furosemide and thiazide showed a good response to furosemide, but little response to thiazide. Although the clinical findings and diuretic tests predicted that the patient had Gitelman syndrome, genetic analysis found no mutation in SLC12A3. However, a novel missense mutation, p.L647F in CLCNKB, which is located in the CBS domain at the C-terminus of ClC-Kb, was discovered. Therefore, gene analyses of CLCNKB and SLC12A3 might be necessary to elucidate the precise etiology of the salt-losing tubulopathies regardless of the results of diuretic tests. We report a patient of Gitelman-like phenotype with chondrocalcinosis. She also showed the insensitivity to thiazide. No mutation in SLC12A3, but a novel mutation, L647F in CLCNKB was discovered. The L647F located in the CBS domain of ClC-Kb. Molecular gene analysis of CLCNKB and SLC12A3 is necessary to the precise etiology.
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Affiliation(s)
- Kumiko Ohkubo
- Department of Laboratory Medicine, Faculty of Medicine, Fukuoka University, Japan ; Department of Clinical Laboratory, Fukuoka University Hospital, Japan
| | - Tomoe Matsuzaki
- Department of Clinical Laboratory, Fukuoka University Hospital, Japan
| | - Makiko Yuki
- Department of Clinical Laboratory, Fukuoka University Hospital, Japan
| | - Ryoko Yoshida
- Department of Endocrinology and Diabetes, Faculty of Medicine, Fukuoka University, Japan
| | - Yuichi Terawaki
- Department of Endocrinology and Diabetes, Faculty of Medicine, Fukuoka University, Japan
| | - Akira Maeyama
- Department of Orthopaedic Surgery, Faculty of Medicine, Fukuoka University, Japan
| | | | - Junko Ono
- Diabetes Center, Karindoh Hospital, Japan
| | - Toshihiko Yanase
- Department of Endocrinology and Diabetes, Faculty of Medicine, Fukuoka University, Japan
| | - Akira Matsunaga
- Department of Laboratory Medicine, Faculty of Medicine, Fukuoka University, Japan ; Department of Clinical Laboratory, Fukuoka University Hospital, Japan
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Jiang L, Chen C, Yuan T, Qin Y, Hu M, Li X, Xing X, Lee X, Nie M, Chen L. Clinical severity of Gitelman syndrome determined by serum magnesium. Am J Nephrol 2014; 39:357-66. [PMID: 24776766 DOI: 10.1159/000360773] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 02/17/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND/AIMS Normomagnesemia is considered atypical in Gitelman syndrome (GS). Here, we describe clinical, pathological and genetic characteristics in Chinese GS patients with or without hypomagnesemia in order to determine whether serum magnesium concentration indicates the severity of the disease. METHODS 7 normomagnesemic and 25 hypomagnesemic GS patients who were confirmed by direct sequencing of SLC12A3 gene were included. Clinical manifestation and laboratory tests were documented. Supine and upright plasma renin activity, angiotensin II and aldosterone were determined by radioimmunoassay. Transient receptor potential channel melastatin subtype 6 (TRPM6) was detected by immunohistochemistry in paraffin-embedded renal biopsy sections of 12 GS patients. 14 patients with glomerular minor lesion served as controls. The distribution of the mutations on the predicted NCC protein was analyzed and compared between two subgroups. RESULTS Clinical manifestations, electrolyte abnormalities, metabolic alkalosis and renin-angiotensin-aldosterone system activation were found to be milder in normomagnesemic compared with the hypomagnesemic group. Compared with glomerular minor lesion controls, the TRPM6-positive area was significantly decreased in hypomagnesemic patients (4.96 ± 1.88 vs. 8.63 ± 2.67%) while it was near normal (7.82 ± 5.23%) in 2 normomagnesemic GS patients. A higher percentage of intracellular mutations was observed in normomagnesemic patients than hypomagnesemic patients (92.31 vs. 56.52%, p = 0.02). CONCLUSIONS Normomagnesemia is not rare in GS. Serum magnesium may indicate the severity of GS.
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Affiliation(s)
- Lanping Jiang
- Department of Nephrology, Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
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