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Boyer O, Ould Rabah M, Preka E. Recent Developments in the Treatment of Pediatric Distal Renal Tubular Acidosis. Paediatr Drugs 2024:10.1007/s40272-024-00651-9. [PMID: 39325135 DOI: 10.1007/s40272-024-00651-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/19/2024] [Indexed: 09/27/2024]
Abstract
Distal renal tubular acidosis (dRTA) is characterized by a primary defect in proton secretion by α-intercalated cells of the collecting duct, leading to impaired urine acidification and resulting in metabolic acidosis, hypokalemia, and hypercalciuria. Inherited forms of dRTA are currently associated with variants in five genes (SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, and WDR72), each being associated with specific extra-renal manifestations. Acquired forms can result from autoimmune diseases or drug side effects. Classical complications include nephrolithiasis, nephrocalcinosis, reduced glomerular filtration rate (GFR), bone demineralization, and growth failure. Treatment focuses on correcting the acid-base imbalance through alkali supplementation (potassium, sodium, or magnesium bicarbonate or citrate) to reduce renal disease progression and promote normal growth and mineralization. Traditional treatments (alkali and potassium supplementation) often suffer from poor adherence due to frequent day and night administrations, gastrointestinal discomfort, and unpleasant taste. A novel investigational drug, ADV7103, which contains potassium citrate and potassium bicarbonate in an extended-release formulation, has recently been approved by the European Medicine Agency (EMA) for dRTA. Recent studies support its use as a first-line treatment, given its efficacy and safety profile.
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Affiliation(s)
- Olivia Boyer
- Néphrologie Pédiatrique, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et l'Adulte (MARHEA), Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (APHP), Institut Imagine, Laboratory of Hereditary Kidney Diseases, INSERM U1163, Université Paris Cité, 149 Rue de Sèvres, 75015, Paris, France.
| | - Mélissa Ould Rabah
- Explorations Fonctionnelles, Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (APHP), Paris, France
| | - Evgenia Preka
- Néphrologie Pédiatrique, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et l'Adulte (MARHEA), Hôpital Universitaire Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (APHP), Institut Imagine, Laboratory of Hereditary Kidney Diseases, INSERM U1163, Université Paris Cité, 149 Rue de Sèvres, 75015, Paris, France
- INSERM U970, PARCC, Paris Translational Research Centre for Organ, Transplantation, Paris, France
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2
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Loeb GB, Kathail P, Shuai RW, Chung R, Grona RJ, Peddada S, Sevim V, Federman S, Mader K, Chu AY, Davitte J, Du J, Gupta AR, Ye CJ, Shafer S, Przybyla L, Rapiteanu R, Ioannidis NM, Reiter JF. Variants in tubule epithelial regulatory elements mediate most heritable differences in human kidney function. Nat Genet 2024:10.1038/s41588-024-01904-6. [PMID: 39256582 DOI: 10.1038/s41588-024-01904-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 08/12/2024] [Indexed: 09/12/2024]
Abstract
Kidney failure, the decrease of kidney function below a threshold necessary to support life, is a major cause of morbidity and mortality. We performed a genome-wide association study (GWAS) of 406,504 individuals in the UK Biobank, identifying 430 loci affecting kidney function in middle-aged adults. To investigate the cell types affected by these loci, we integrated the GWAS with human kidney candidate cis-regulatory elements (cCREs) identified using single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq). Overall, 56% of kidney function heritability localized to kidney tubule epithelial cCREs and an additional 7% to kidney podocyte cCREs. Thus, most heritable differences in adult kidney function are a result of altered gene expression in these two cell types. Using enhancer assays, allele-specific scATAC-seq and machine learning, we found that many kidney function variants alter tubule epithelial cCRE chromatin accessibility and function. Using CRISPRi, we determined which genes some of these cCREs regulate, implicating NDRG1, CCNB1 and STC1 in human kidney function.
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Affiliation(s)
- Gabriel B Loeb
- Division of Nephrology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
| | - Pooja Kathail
- Center for Computational Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Richard W Shuai
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ryan Chung
- Center for Computational Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Reinier J Grona
- Division of Nephrology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Sailaja Peddada
- Laboratory for Genomics Research, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Volkan Sevim
- Laboratory for Genomics Research, San Francisco, CA, USA
- Target Discovery, GSK, San Francisco, CA, USA
| | - Scot Federman
- Laboratory for Genomics Research, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Karl Mader
- Laboratory for Genomics Research, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Audrey Y Chu
- Human Genetics and Genomics, GSK, Cambridge, MA, USA
| | | | - Juan Du
- Department of Surgery, University of California, San Francisco, San Francisco, CA, USA
| | - Alexander R Gupta
- Department of Surgery, University of California, San Francisco, San Francisco, CA, USA
| | - Chun Jimmie Ye
- Division of Rheumatology, Department of Medicine; Bakar Computational Health Sciences Institute; Parker Institute for Cancer Immunotherapy; Institute for Human Genetics; Department of Epidemiology & Biostatistics; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
- Arc Institute, Palo Alto, CA, USA
| | - Shawn Shafer
- Laboratory for Genomics Research, San Francisco, CA, USA
- Target Discovery, GSK, San Francisco, CA, USA
| | - Laralynne Przybyla
- Laboratory for Genomics Research, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Radu Rapiteanu
- Genome Biology, Research Technologies, GSK, Stevenage, UK
| | - Nilah M Ioannidis
- Center for Computational Biology, University of California, Berkeley, Berkeley, CA, USA
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Jeremy F Reiter
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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3
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Carpentieri G, Cecchetti S, Bocchinfuso G, Radio FC, Leoni C, Onesimo R, Calligari P, Pietrantoni A, Ciolfi A, Ferilli M, Calderan C, Cappuccio G, Martinelli S, Messina E, Caputo V, Hüffmeier U, Mignot C, Auvin S, Capri Y, Lourenco CM, Russell BE, Neustad A, Brunetti Pierri N, Keren B, Reis A, Cohen JS, Heidlebaugh A, Smith C, Thiel CT, Salviati L, Zampino G, Campeau PM, Stella L, Tartaglia M, Flex E. Dominantly acting variants in ATP6V1C1 and ATP6V1B2 cause a multisystem phenotypic spectrum by altering lysosomal and/or autophagosome function. HGG ADVANCES 2024; 5:100349. [PMID: 39210597 DOI: 10.1016/j.xhgg.2024.100349] [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: 06/06/2024] [Revised: 08/27/2024] [Accepted: 08/27/2024] [Indexed: 09/04/2024] Open
Abstract
The vacuolar H+-ATPase (V-ATPase) is a functionally conserved multimeric complex localized at the membranes of many organelles where its proton-pumping action is required for proper lumen acidification. The V-ATPase complex is composed of several subunits, some of which have been linked to human disease. We and others previously reported pathogenic dominantly acting variants in ATP6V1B2, the gene encoding the V1B2 subunit, as underlying a clinically variable phenotypic spectrum including dominant deafness-onychodystrophy (DDOD) syndrome, Zimmermann-Laband syndrome (ZLS), and deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures (DOORS) syndrome. Here, we report on an individual with features fitting DOORS syndrome caused by dysregulated ATP6V1C1 function, expand the clinical features associated with ATP6V1B2 pathogenic variants, and provide evidence that these ATP6V1C1/ATP6V1B2 amino acid substitutions result in a gain-of-function mechanism upregulating V-ATPase function that drives increased lysosomal acidification. We demonstrate a disruptive effect of these ATP6V1B2/ATP6V1C1 variants on lysosomal morphology, localization, and function, resulting in a defective autophagic flux and accumulation of lysosomal substrates. We also show that the upregulated V-ATPase function affects cilium biogenesis, further documenting pleiotropy. This work identifies ATP6V1C1 as a new gene associated with a neurodevelopmental phenotype resembling DOORS syndrome, documents the occurrence of a phenotypic continuum between ZLS, and DDOD and DOORS syndromes, and classify these conditions as lysosomal disorders.
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Affiliation(s)
- Giovanna Carpentieri
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy; Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Serena Cecchetti
- Confocal Microscopy Unit, Core Facilities, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Gianfranco Bocchinfuso
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy
| | | | - Chiara Leoni
- Center for Rare Diseases and Birth Defects, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome 00168, Italy
| | - Roberta Onesimo
- Center for Rare Diseases and Birth Defects, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome 00168, Italy
| | - Paolo Calligari
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Agostina Pietrantoni
- Electron Microscopy Unit, Core Facilities, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Andrea Ciolfi
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Marco Ferilli
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Cristina Calderan
- Department of Women and Children's Health, University of Padua, Fondazione Istituto di Ricerca Pediatrica Città della Speranza, 35127 Padua, Italy
| | - Gerarda Cappuccio
- Department of Translational Medicine, "Federico II" University, 80131 Naples, Italy
| | - Simone Martinelli
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Elena Messina
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Viviana Caputo
- Department of Experimental Medicine, Sapienza University of Rome, 00185 Rome, Italy
| | - Ulrike Hüffmeier
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Cyril Mignot
- Department of Genetics, La Pitié-Salpêtrière Hospital, Assistance Publique-Hopitaux de Paris, Sorbonne University, Paris, France
| | - Stéphane Auvin
- Service de Neurologie Pediatrique, Hopital Universitaire Robert Debré, Université Paris Cité, 75935 Paris, France
| | - Yline Capri
- Department of Genetics, Robert-Debré University Hospital, Assistance Publique-Hopitaux de Paris, 75935 Paris, France
| | - Charles Marques Lourenco
- Faculdade de Medicina, Centro Universitario Estácio de Ribeirão Preto, Ribeirão Preto 14096-160, São Paulo, Brazil
| | - Bianca E Russell
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ahna Neustad
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Nicola Brunetti Pierri
- Department of Translational Medicine, "Federico II" University, 80131 Naples, Italy; Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Naples, Italy; Scuola Superiore Meridionale, Genomics and Experimental Medicine Program, University of Naples Federico II, Naples, Italy
| | - Boris Keren
- Department of Genetics, La Pitié-Salpêtrière Hospital, Assistance Publique-Hopitaux de Paris, Sorbonne University, Paris, France
| | - André Reis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Julie S Cohen
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Alexis Heidlebaugh
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD 21205, USA
| | - Clay Smith
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Christian T Thiel
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg FAU, 91054 Erlangen, Germany
| | - Leonardo Salviati
- Department of Women and Children's Health, University of Padua, Fondazione Istituto di Ricerca Pediatrica Città della Speranza, 35127 Padua, Italy
| | - Giuseppe Zampino
- Center for Rare Diseases and Birth Defects, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome 00168, Italy; Facoltà di Medicina e Chirurgia, Università Cattolica del S. Cuore, 00168 Rome, Italy
| | | | - Lorenzo Stella
- Department of Chemical Science and Technologies, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy.
| | - Elisabetta Flex
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy.
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Mukherjee S, Arjunan D, Bhadada S, Shaharyar A. Unusual presentation of Sjogren's syndrome. BMJ Case Rep 2024; 17:e256661. [PMID: 38960417 DOI: 10.1136/bcr-2023-256661] [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] [Indexed: 07/05/2024] Open
Abstract
Sjogren's syndrome is a known cause of renal tubular acidosis (RTA). However, osteomalacia associated with Sjogren's syndrome is rare and seldom reported in literature. We report a case of pseudofractures of both femora due to osteomalacia as a result of RTA secondary to Sjogren's syndrome, which was initially misdiagnosed as a stress fracture. A man in his 30s presented with hip pain and was initially misdiagnosed to have stress fractures because of the 'through and through' extension of the 'fracture' lines at the neck of both femora. The patient had a normal serum biochemistry profile except for elevated alkaline phosphatase levels. On further evaluation, he was found to have distal RTA secondary to Sjogren's syndrome. The patient responded to sodium bicarbonate therapy with clinical, biochemical and radiological improvement. A high index of suspicion for RTA should be kept in a patient with osteomalacia with a normal calcium profile and vitamin D level.
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Affiliation(s)
- Soham Mukherjee
- Endocrinology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Durairaj Arjunan
- Endocrinology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Sanjay Bhadada
- Endocrinology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Amal Shaharyar
- Endocrinology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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5
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Mungara P, Waiss M, Hartwig S, Burger D, Cordat E. Unraveling the molecular landscape of kAE1: a narrative review. Can J Physiol Pharmacol 2024; 102:396-407. [PMID: 38669699 DOI: 10.1139/cjpp-2023-0482] [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] [Indexed: 04/28/2024]
Abstract
Kidney anion exchanger 1 (kAE1) is an isoform of the AE1 protein encoded by the SLC4A1 gene. It is a basolateral membrane protein expressed by α-intercalated cells in the connecting tubules and collecting duct of the kidney. Its main function is to exchange bicarbonate and chloride ions between the blood and urine to maintain blood pH at physiological threshold. The kAE1 protein undergoes multiple post-translational modifications such as phosphorylation and ubiquitination and interacts with many different proteins such as claudin-4 and carbonic anhydrase II. Mutations in the gene may lead to the development of distal renal tubular acidosis, characterized by the failure to acidify the urine, which may result in nephrocalcinosis and in more severe cases, renal failure. In this review, we discuss the structure and function of kAE1, its post-translational modifications, and protein-protein interactions. Finally, we discuss insights gained from the study of kAE1 mutations in humans and in mice.
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Affiliation(s)
- Priyanka Mungara
- Department of Physiology, Membrane Protein Disease Research Group, Faculty of Medicine, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Moubarak Waiss
- School of Pharmaceutical Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Sunny Hartwig
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Dylan Burger
- School of Pharmaceutical Sciences, University of Ottawa, Ottawa, ON, Canada
- Ottawa Hospital Research Institute, Kidney Research Centre, Ottawa, ON, Canada
| | - Emmanuelle Cordat
- Department of Physiology, Membrane Protein Disease Research Group, Faculty of Medicine, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
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6
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Chen PL, Huang KT, Chen LY, Hsu K. Erythroid anion Exchanger-1 (band 3) transports nitrite for nitric oxide metabolism. Free Radic Biol Med 2024; 210:237-245. [PMID: 38042224 DOI: 10.1016/j.freeradbiomed.2023.11.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/23/2023] [Accepted: 11/26/2023] [Indexed: 12/04/2023]
Abstract
Nitrite (NO2-) interacts with hemoglobin (Hb) in various ways to regulate blood flow. During hypoxic vasodilation, nitrite is reduced by deoxyHb to yield nitric oxide (NO). While NO, a hydrophobic gas, could freely diffuse across the cell membrane, how the reactant nitrite anion could permeate through the red blood cell (RBC) membrane remains unclear. We hypothesized that Cl-/HCO3- anion exchanger-1 (AE1; band 3) abundantly embedded in the RBC membrane could transport NO2-, as HCO3- and NO2- exhibit similar hydrated radii. Here, we monitored NO/N2O3 generated from NO2- inside human RBCs by DAF-FM fluorophore. NO2-, not NO3-, increased intraerythrocytic DAF-FM fluorescence. To test the involvement of AE1-mediated transport in intraerythrocytic NO/N2O3 production from nitrite, we lowered Cl- or HCO3- in the RBC-incubating buffer by 20 % and indeed observed slower rise of the DAF-FM fluorescence. Anti-extracellular AE1, but not anti-intracellular AE1 antibodies, reduced the rates of NO formation from nitrite. The AE1 blocker DIDS similarly reduced the rates of NO/N2O3 production from nitrite in a dose-dependent fashion, confirming that nitrite entered RBCs through AE1. Nitrite inside the RBCs reacted with both deoxyHb and oxyHb, as evidenced by 6.1 % decrease in deoxyHb, 14.7 % decrease in oxyHb, and 20.7 % increase in methemoglobin (metHb). Lowering Cl- in the milieu equally delayed metHb production from nitrite-oxyHb and nitrite-deoxyHb reactions. Thus, AE1-mediated NO2- transport facilitates NO2--Hb reactions inside the red cells, supporting NOx metabolism in circulation.
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Affiliation(s)
- Pin-Lung Chen
- The Laboratory of Immunogenetics, Department of Medical Research, MacKay Memorial Hospital, Tamsui, New Taipei City, Taiwan
| | - Kuang-Tse Huang
- Department of Chemical Engineering, National Chung-Cheng University, Chia-Yi, Taiwan
| | - Li-Yang Chen
- The Laboratory of Immunogenetics, Department of Medical Research, MacKay Memorial Hospital, Tamsui, New Taipei City, Taiwan
| | - Kate Hsu
- The Laboratory of Immunogenetics, Department of Medical Research, MacKay Memorial Hospital, Tamsui, New Taipei City, Taiwan; MacKay Junior College of Medicine, Nursing, and Management, New Taipei City, Taiwan; Institute of Biomedical Sciences, MacKay Medical College, New Taipei City, Taiwan.
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7
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Guo W, Ji P, Xie Y. Genetic Diagnosis and Treatment of Inherited Renal Tubular Acidosis. KIDNEY DISEASES (BASEL, SWITZERLAND) 2023; 9:371-383. [PMID: 37901710 PMCID: PMC10601937 DOI: 10.1159/000531556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/12/2023] [Indexed: 10/31/2023]
Abstract
Background Renal tubular acidosis (RTA) is caused by various disruptions to the secretion of H+ by distal renal tubules and/or dysfunctional reabsorption of HCO3- by proximal renal tubules, which causes renal acidification dysfunction, ultimately leading to a clinical syndrome characterized by hyperchloremic metabolic acidosis with a normal anion gap. With the development of molecular genetics and gene sequencing technology, inherited RTA has also attracted attention, and an increasing number of RTA-related pathogenic genes have been discovered and reported. Summary This paper focuses on the latest progress in the research of inherited RTA and systematically reviews the pathogenic genes, protein functions, clinical manifestations, internal relationship between genotypes and clinical phenotypes, diagnostic clues, differential diagnosis, and treatment strategies associated with inherited RTA. This paper aims to deepen the understanding of inherited RTA and reduce the missed diagnosis and misdiagnosis of RTA. Key Messages This review systematically summarizes the pathogenic genes, pathophysiological mechanisms, differential diagnosis, and treatment of different types of inherited RTA, which has good clinical value for guiding the diagnosis and treatment of inherited RTA.
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Affiliation(s)
- Wenkai Guo
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, China
- School of Medicine, Nankai University, Tianjin, China
| | - Pengcheng Ji
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, China
| | - Yuansheng Xie
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, China
- School of Medicine, Nankai University, Tianjin, China
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Guerra Hernández NE, Gómez Tenorio C, Méndez Silva LP, Moraleda Mesa T, Escobar LI, Salvador C, Vargas Poussou R, García Nieto VM. Autosomal dominant distal renal tubular acidosis in two pediatric patients with mutations in the SLC4A1 gene. Can the maximum urinary pCO 2 test be normal? Nefrologia 2023; 43:484-490. [PMID: 37775346 DOI: 10.1016/j.nefroe.2023.08.006] [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: 05/12/2021] [Accepted: 09/06/2021] [Indexed: 10/01/2023] Open
Abstract
Primary distal renal tubular acidosis (dRTA) is a rare tubulopathy characterised by the presence of hyperchloremic metabolic acidosis. It is caused by the existence of a defect in the function of the H+ -ATPase located on the luminal side of the α-intercalated cells or the Cl - HCO3- (AE1) anion exchanger located on the basolateral side. Patients do not acidify the urine after acid overload (NH4Cl) or after stimulating H+ secretion by obtaining a high intratubular concentration of an anion such as chlorine (pH is measured) or HCO3- (urinary pCO2 is measured). We present a family with autosomal dominant dRTA produced by a heterozygous mutation in the SLC4A1 gene in which the two paediatric members showed a test of normal maximum urinary pCO2. Our hypothesis is that since the H + -ATPase is intact, at least initially, the stimulation induced by intratubular electronegativity to secrete H + could be effective, which would allow the maximum urinary pCO2 to be paradoxically normal, which could explain the onset, moderate presentation of symptoms and late diagnosis in patients with this mutation. This is the first documented case of a dominant dRTA in Mexico.
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Affiliation(s)
- Norma E Guerra Hernández
- Servicio de Nefrología Pediátrica, Hospital General del Centro Médico Nacional «La Raza», Instituto Mexicano del Seguro Social, Ciudad de México, Mexico.
| | - Circe Gómez Tenorio
- Servicio de Nefrología Pediátrica, Hospital General del Centro Médico Nacional «La Raza», Instituto Mexicano del Seguro Social, Ciudad de México, Mexico; Servicio de Nefrología Pediátrica, Hospital Hospital de Ginecología No. 48, Instituto Mexicano del Seguro Social, León, Guanajuato, Mexico
| | - Laura Paloma Méndez Silva
- Servicio de Nefrología Pediátrica, Hospital Hospital de Ginecología No. 48, Instituto Mexicano del Seguro Social, León, Guanajuato, Mexico
| | - Teresa Moraleda Mesa
- Servicio de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de la Candelaria, Santa Cruz de Tenerife, Tenerife, Spain
| | - Laura I Escobar
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Carolina Salvador
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Víctor M García Nieto
- Servicio de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de la Candelaria, Santa Cruz de Tenerife, Tenerife, Spain
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9
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Wagner CA, Unwin R, Lopez-Garcia SC, Kleta R, Bockenhauer D, Walsh S. The pathophysiology of distal renal tubular acidosis. Nat Rev Nephrol 2023; 19:384-400. [PMID: 37016093 DOI: 10.1038/s41581-023-00699-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/06/2023]
Abstract
The kidneys have a central role in the control of acid-base homeostasis owing to bicarbonate reabsorption and production of ammonia and ammonium in the proximal tubule and active acid secretion along the collecting duct. Impaired acid excretion by the collecting duct system causes distal renal tubular acidosis (dRTA), which is characterized by the failure to acidify urine below pH 5.5. This defect originates from reduced function of acid-secretory type A intercalated cells. Inherited forms of dRTA are caused by variants in SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, WDR72 and probably in other genes that are yet to be discovered. Inheritance of dRTA follows autosomal-dominant and -recessive patterns. Acquired forms of dRTA are caused by various types of autoimmune diseases or adverse effects of some drugs. Incomplete dRTA is frequently found in patients with and without kidney stone disease. These patients fail to appropriately acidify their urine when challenged, suggesting that incomplete dRTA may represent an intermediate state in the spectrum of the ability to excrete acids. Unrecognized or insufficiently treated dRTA can cause rickets and failure to thrive in children, osteomalacia in adults, nephrolithiasis and nephrocalcinosis. Electrolyte disorders are also often present and poorly controlled dRTA can increase the risk of developing chronic kidney disease.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK.
| | - Robert Unwin
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Sergio C Lopez-Garcia
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Robert Kleta
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Detlef Bockenhauer
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Stephen Walsh
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
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10
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Yang M, Sheng Q, Ge S, Song X, Dong J, Guo C, Liao L. Mutations and clinical characteristics of dRTA caused by SLC4A1 mutations: Analysis based on published patients. Front Pediatr 2023; 11:1077120. [PMID: 36776909 PMCID: PMC9910804 DOI: 10.3389/fped.2023.1077120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 01/06/2023] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND AND AIMS The genetic and clinical characteristics of patients with distal renal tubular acidosis (dRTA) caused by SLC4A1 mutations have not been systematically recorded before. Here, we summarized the SLC4A1 mutations and clinical characteristics associated with dRTA. METHODS Database was searched, and the mutations and clinical manifestations of patients were summarized from the relevant articles. RESULTS Fifty-three eligible articles involving 169 patients were included and 41 mutations were identified totally. Fifteen mutations involving 100 patients were autosomal dominant inheritance, 21 mutations involving 61 patients were autosomal recessive inheritance. Nephrocalcinosis or kidney stones were found in 72.27%, impairment in renal function in 14.29%, developmental disorders in 61.16%, hematological abnormalities in 33.88%, and muscle weakness in 13.45% of patients. The age of onset was younger (P < 0.01), urine pH was higher (P < 0.01), and serum potassium was lower (P < 0.001) in recessive patients than patients with dominant SLC4A1 mutations. Autosomal recessive inheritance was more often found in Asian patients (P < 0.05). CONCLUSIONS The children present with metabolic acidosis with high urinary pH, accompanying hypokalemia, hyperchloremia, nephrocalcinosis, growth retardation and hematological abnormalities should be suspected as dRTA and suggested a genetic testing. The patients with recessive dRTA are generally more severely affected than that with dominant SLC4A1 mutations. Autosomal recessive inheritance was more often found in Asian patients, and more attentions should be paid to the Asian patients.
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Affiliation(s)
- Mengge Yang
- Department of Endocrinology and Metabology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Ji-nan, China.,Cheeloo College of Medicine, Shandong University, Department of Endocrinology and Metabology, Shandong Provincial Qianfoshan Hospital, Shandong Key Laboratory of Rheumatic Disease and Translational Medicine, Shandong Institute of Nephrology, Ji-nan, China
| | - Qiqi Sheng
- Division of Endocrinology, Department of Internal Medicine, Qilu Hospital of Shandong University, Ji-nan, China
| | - Shenghui Ge
- Department of Endocrinology and Metabology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Ji-nan, China
| | - Xinxin Song
- College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Ji-nan, China
| | - Jianjun Dong
- Division of Endocrinology, Department of Internal Medicine, Qilu Hospital of Shandong University, Ji-nan, China
| | - Congcong Guo
- Department of Endocrinology and Metabology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Ji-nan, China.,College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Ji-nan, China
| | - Lin Liao
- Department of Endocrinology and Metabology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Ji-nan, China.,Cheeloo College of Medicine, Shandong University, Department of Endocrinology and Metabology, Shandong Provincial Qianfoshan Hospital, Shandong Key Laboratory of Rheumatic Disease and Translational Medicine, Shandong Institute of Nephrology, Ji-nan, China.,College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Ji-nan, China
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11
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Tabibzadeh N, Crambert G. Mechanistic insights into the primary and secondary alterations of renal ion and water transport in the distal nephron. J Intern Med 2023; 293:4-22. [PMID: 35909256 PMCID: PMC10087581 DOI: 10.1111/joim.13552] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The kidneys, by equilibrating the outputs to the inputs, are essential for maintaining the constant volume, pH, and electrolyte composition of the internal milieu. Inability to do so, either because of internal kidney dysfunction (primary alteration) or because of some external factors (secondary alteration), leads to pathologies of varying severity, leading to modification of these parameters and affecting the functions of other organs. Alterations of the functions of the collecting duct (CD), the most distal part of the nephron, have been extensively studied and have led to a better diagnosis, better management of the related diseases, and the development of therapeutic tools. Thus, dysfunctions of principal cell-specific transporters such as ENaC or AQP2 or its receptors (mineralocorticoid or vasopressin receptors) caused by mutations or by compounds present in the environment (lithium, antibiotics, etc.) have been demonstrated in a variety of syndromes (Liddle, pseudohypoaldosteronism type-1, diabetes insipidus, etc.) affecting salt, potassium, and water balance. In parallel, studies on specific transporters (H+ -ATPase, anion exchanger 1) in intercalated cells have revealed the mechanisms of related tubulopathies like distal renal distal tubular acidosis or Sjögren syndrome. In this review, we will recapitulate the mechanisms of most of the primary and secondary alteration of the ion transport system of the CD to provide a better understanding of these diseases and highlight how a targeted perturbation may affect many different pathways due to the strong crosstalk and entanglements between the different actors (transporters, cell types).
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Affiliation(s)
- Nahid Tabibzadeh
- Laboratoire de Physiologie Rénale et TubulopathiesCentre de Recherche des CordeliersINSERMSorbonne UniversitéUniversité Paris CitéParisFrance
- EMR 8228 Unité Métabolisme et Physiologie RénaleCNRSParisFrance
- Assistance Publique Hôpitaux de ParisHôpital BichâtParisFrance
| | - Gilles Crambert
- Laboratoire de Physiologie Rénale et TubulopathiesCentre de Recherche des CordeliersINSERMSorbonne UniversitéUniversité Paris CitéParisFrance
- EMR 8228 Unité Métabolisme et Physiologie RénaleCNRSParisFrance
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12
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Li J, Wang X, Zheng N, Wang X, Liu Y, Xue L. A novel variant of SLC4A1 for hereditary spherocytosis in a Chinese family: a case report and systematic review. BMC Med Genomics 2022; 15:250. [PMID: 36463227 PMCID: PMC9719243 DOI: 10.1186/s12920-022-01399-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/14/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND The incidence of hereditary spherocytosis (HS) is approximately 1:2000 in the western population, while it is much lower in the Chinese population. It is difficult to make a definite diagnosis due to the variable genotypic features and the lack of well-documented evidence for HS patients. Gene sequence examination is helpful for clear diagnosis. CASE PRESENTATION We presented the case of a 29-year-old male HS patient with skin yellowness, anorexia, and cholecystolithiasis as the first manifestations. Laboratory examination of the patient and his parents showed a mild reduction in hemoglobin and mean corpuscular hemoglobin concentration, increased reticulocytes, and promotion of indirect bilirubin in the patient and his father. Furthermore, small globular red blood cells with increased osmotic fragility were observed. In particular, the eosin-5'-maleimide binding test provided the strong evidence that band 3 protein was deleted in the erythrocyte membrane. Next-generation sequencing (NGS) and Sanger sequencing further demonstrated a heterozygous nonsense variant (exon16, c.G1985A: p.W662X) in SLC4A1, inherited from his father. Thus, the patient was diagnosed with HS, and then was effectively treated. After splenectomy, the anemia was relieved without any obvious unpleasant side effects. CONCLUSION We report an extremely rare case of HS in China that presented with hereditary hemolytic anemia with band 3 deletion resulting from a novel variant of SLC4A1, and systematically review a large number of related literatures. This study, therefore, significantly contributes to the literature on HS.
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Affiliation(s)
- Jie Li
- Department of Hematology, Hebei General Hospital, 348 West Heping Road, 050000, Shijiazhuang, China.
| | - Xiaozi Wang
- Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, 050000, Shijiazhuang, China
| | - Na Zheng
- Department of Hematology, Hebei General Hospital, 348 West Heping Road, 050000, Shijiazhuang, China
| | - Xiaoning Wang
- Department of Hematology, Hebei General Hospital, 348 West Heping Road, 050000, Shijiazhuang, China
| | - Yan Liu
- Department of Hematology, Hebei General Hospital, 348 West Heping Road, 050000, Shijiazhuang, China
| | - Liying Xue
- Laboratory of Pathology, Hebei Medical University, No. 361, Zhongshan Eastern Road, 050000, Shijiazhuang, China.
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13
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Deejai N, Sawasdee N, Nettuwakul C, Wanachiwanawin W, Sritippayawan S, Yenchitsomanus PT, Rungroj N. Impaired trafficking and instability of mutant kidney anion exchanger 1 proteins associated with autosomal recessive distal renal tubular acidosis. BMC Med Genomics 2022; 15:228. [PMID: 36320073 PMCID: PMC9623938 DOI: 10.1186/s12920-022-01381-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022] Open
Abstract
Background Mutations in solute carrier family 4 member 1 (SLC4A1) encoding anion exchanger 1 (AE1) are the most common cause of autosomal recessive distal renal tubular acidosis (AR dRTA) in Southeast Asians. To explain the molecular mechanism of this disease with hematological abnormalities in an affected family, we conducted a genetic analysis of SLC4A1 and studied wild-type and mutant AE1 proteins expressed in human embryonic kidney 293T (HEK293T) cells. Methods SLC4A1 mutations in the patient and family members were analyzed by molecular genetic techniques. Protein structure modeling was initially conducted to evaluate the effects of mutations on the three-dimensional structure of the AE1 protein. The mutant kidney anion exchanger 1 (kAE1) plasmid construct was created to study protein expression, localization, and stability in HEK293T cells. Results We discovered that the patient who had AR dRTA coexisting with mild hemolytic anemia carried a novel compound heterozygous SLC4A1 mutations containing c.1199_1225del (p.Ala400_Ala408del), resulting in Southeast Asian ovalocytosis (SAO), and c.1331C > A (p.Thr444Asn). Homologous modeling and in silico mutagenesis indicated that these two mutations affected the protein structure in the transmembrane regions of kAE1. We found the wild-type and mutant kAE1 T444N to be localized at the cell surface, whereas the mutants kAE1 SAO and SAO/T444N were intracellularly retained. The half-life of the kAE1 SAO, T444N, and SAO/T444N mutants was shorter than that of the wild-type protein. Conclusion These results suggest impaired trafficking and instability of kAE1 SAO/T444N as the likely underlying molecular mechanism explaining the pathogenesis of the novel SLC4A1 compound heterozygous mutation identified in this patient. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-022-01381-y.
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Affiliation(s)
- Nipaporn Deejai
- grid.10223.320000 0004 1937 0490Division of Molecular Medicine, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nunghathai Sawasdee
- grid.10223.320000 0004 1937 0490Division of Molecular Medicine, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Choochai Nettuwakul
- grid.10223.320000 0004 1937 0490Division of Molecular Medicine, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Wanchai Wanachiwanawin
- grid.10223.320000 0004 1937 0490Division of Hematology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Suchai Sritippayawan
- grid.10223.320000 0004 1937 0490Division of Nephrology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Pa-thai Yenchitsomanus
- grid.10223.320000 0004 1937 0490Division of Molecular Medicine, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nanyawan Rungroj
- grid.10223.320000 0004 1937 0490Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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14
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Hammi Y, Charfi H, Ferjani M, Sayari T, Mrad R, Gargah T. Particularités épidémiologiques, cliniques et évolutives de l’acidose tubulaire distale primitive chez l’enfant tunisien. Nephrol Ther 2022; 18:541-548. [DOI: 10.1016/j.nephro.2022.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 03/18/2022] [Accepted: 03/23/2022] [Indexed: 11/07/2022]
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15
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Guerra Hernández NE, Gómez Tenorio C, Méndez Silva LP, Moraleda Mesa T, Escobar LI, Salvador C, Vargas Poussou R, García Nieto VM. Acidosis tubular renal distal autosómica dominante en dos pacientes pediátricos con mutaciones en el gen SLC4A1. ¿La prueba de la pCO2 urinaria máxima puede ser normal? Nefrologia 2021. [DOI: 10.1016/j.nefro.2021.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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16
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Cogal AG, Arroyo J, Shah RJ, Reese KJ, Walton BN, Reynolds LM, Kennedy GN, Seide BM, Senum SR, Baum M, Erickson SB, Jagadeesh S, Soliman NA, Goldfarb DS, Beara-Lasic L, Edvardsson VO, Palsson R, Milliner DS, Sas DJ, Lieske JC, Harris PC. Comprehensive Genetic Analysis Reveals Complexity of Monogenic Urinary Stone Disease. Kidney Int Rep 2021; 6:2862-2884. [PMID: 34805638 PMCID: PMC8589729 DOI: 10.1016/j.ekir.2021.08.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/24/2021] [Accepted: 08/30/2021] [Indexed: 01/06/2023] Open
Abstract
Introduction Because of phenotypic overlap between monogenic urinary stone diseases (USD), gene-specific analyses can result in missed diagnoses. We used targeted next generation sequencing (tNGS), including known and candidate monogenic USD genes, to analyze suspected primary hyperoxaluria (PH) or Dent disease (DD) patients genetically unresolved (negative; N) after Sanger analysis of the known genes. Cohorts consisted of 285 PH (PHN) and 59 DD (DDN) families. Methods Variants were assessed using disease-specific and population databases plus variant assessment tools and categorized using the American College of Medical Genetics (ACMG) guidelines. Prior Sanger analysis identified 47 novel PH or DD gene pathogenic variants. Results Screening by tNGS revealed pathogenic variants in 14 known monogenic USD genes, accounting for 45 families (13.1%), 27 biallelic and 18 monoallelic, including 1 family with a copy number variant (CNV). Recurrent genes included the following: SLC34A3 (n = 13), CLDN16 (n = 8), CYP24A1 (n = 4), SLC34A1 (n = 3), SLC4A1 (n = 3), APRT (n = 2), CLDN19 (n = 2), HNF4A1 (n = 2), and KCNJ1 (n = 2), whereas ATP6V1B1, CASR, and SLC12A1 and missed CNVs in the PH genes AGXT and GRHPR accounted for 1 pedigree each. Of the 48 defined pathogenic variants, 27.1% were truncating and 39.6% were novel. Most patients were diagnosed before 18 years of age (76.1%), and 70.3% of biallelic patients were homozygous, mainly from consanguineous families. Conclusion Overall, in patients suspected of DD or PH, 23.9% and 7.3% of cases, respectively, were caused by pathogenic variants in other genes. This study shows the value of a tNGS screening approach to increase the diagnosis of monogenic USD, which can optimize therapies and facilitate enrollment in clinical trials.
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Affiliation(s)
- Andrea G Cogal
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Jennifer Arroyo
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Ronak Jagdeep Shah
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kalina J Reese
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Brenna N Walton
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Laura M Reynolds
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Gabrielle N Kennedy
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Barbara M Seide
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Sarah R Senum
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Stephen B Erickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology and Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - David S Goldfarb
- Nephrology Division, New York University Langone Health and New York University School of Medicine, New York, New York, USA
| | - Lada Beara-Lasic
- Nephrology Division, New York University Langone Health and New York University School of Medicine, New York, New York, USA
| | - Vidar O Edvardsson
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.,Children's Medical Center, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | - Runolfur Palsson
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.,Division of Nephrology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | - Dawn S Milliner
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - David J Sas
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.,Division of Pediatric Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - John C Lieske
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.,Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Peter C Harris
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
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17
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Gómez-Conde S, García-Castaño A, Aguirre M, Herrero M, Gondra L, García-Pérez N, García-Ledesma P, Martín-Penagos L, Dall'Anese C, Ariceta G, Castaño L, Madariaga L. Molecular aspects and long-term outcome of patients with primary distal renal tubular acidosis. Pediatr Nephrol 2021; 36:3133-3142. [PMID: 33881640 DOI: 10.1007/s00467-021-05066-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal mechanisms of urinary acidification. Most cases are secondary to pathogenic variants in ATP6V0A4, ATP6V1B1, and SLC4A1 genes, which encode transporters regulating acid-base balance in the collecting duct. METHODS Retrospective study of molecular and clinical data from diagnosis and long-term follow-up (10, 20, and 40±10 years) of 16 patients with primary dRTA diagnosed in childhood. RESULTS Molecular analyses revealed nine patients had ATP6V0A4 pathogenic variants, five in ATP6V1B1, and two in SLC4A1. A novel intragenic deletion and a common ATP6V0A4 gene variant (c.1691 + 2dupT) in ATP6V0A4 occurred in two-thirds of these patients, suggesting a founder effect. Median age at diagnosis was 3.25 months (IQR 1, 13.5), which was higher in the SLC4A1 group. Median SDS height at diagnosis was -1.02 (IQR -1.79, 0.14). Delayed clinical diagnosis was significantly related to growth failure (P = 0.01). Median SDS height at 20 years follow-up was -1.23 (IQR -1.71, -0.48), and did not significantly improve from diagnosis (P = 0.76). Kidney function declined over time: at last follow-up, 43% had moderate to severe chronic kidney disease (CKD). Adequate metabolic control was not related to CKD development. Incidence of sensorineural hearing loss (SNHL) was high in ATP6V1B1 patients, though not universal. Patients harboring ATP6V0A4 variants also developed SNHL at a high rate (80%) over time. CONCLUSIONS Patients with dRTA can develop moderate to severe CKD over time with a high frequency despite adequate metabolic control. Early diagnosis ameliorates long-term height prognosis.
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Affiliation(s)
| | - Alejandro García-Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
| | - Mireia Aguirre
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain
| | - María Herrero
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain
| | - Leire Gondra
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Nélida García-Pérez
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain.,Pediatric Nephrology Department, Basurto University Hospital, Bilbao, Spain
| | | | - Luis Martín-Penagos
- Nephrology Department, Marqués de Valdecilla University Hospital, Santander, Spain
| | | | - Gema Ariceta
- Pediatric Nephrology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Leire Madariaga
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain. .,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain. .,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain. .,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain.
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18
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Trepiccione F, Walsh SB, Ariceta G, Boyer O, Emma F, Camilla R, Ferraro PM, Haffner D, Konrad M, Levtchenko E, Lopez-Garcia SC, Santos F, Stabouli S, Szczepanska M, Tasic V, Topaloglu R, Vargas-Poussou R, Wlodkowski T, Bockenhauer D. Distal Renal Tubular Acidosis: ERKNet/ESPN Clinical Practice Points. Nephrol Dial Transplant 2021; 36:1585-1596. [PMID: 33914889 DOI: 10.1093/ndt/gfab171] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Indexed: 12/15/2022] Open
Abstract
Distal renal tubular acidosis (dRTA) is characterised by an impaired ability of the distal tubule to excrete acid, leading to metabolic acidosis. Associated complications include bone disease, growth failure, urolithiasis and hypokalaemia. Due to its rarity, there is a limited evidence to guide diagnosis and management, however, available data strongly suggest that metabolic control of the acidosis by alkali supplementation can halt or revert almost all complications. Despite this, cohort studies show that adequate metabolic control is present in only about half of patients, highlighting problems with treatment provision or adherence. With these clinical practice points the authors, part of the working groups tubulopathies in the European Rare Kidney Disease Reference network (ERKnet) and inherited kidney diseases of the European Society for Paediatric Nephrology (ESPN) aim to provide guidance for the management of patients with dRTA to facilitate adequate treatment and establish an initial best practice standard against which treatment of patients can be audited.
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Affiliation(s)
- Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "L. Vanvitelli", Naples, Italy
| | - Steven B Walsh
- Department of Renal Medicine, University College London, UK
| | - Gema Ariceta
- Division of Pediatric Nephrology. Hospital Universitario Vall d' Hebron. Universitat Autonoma de Barcelona. Barcelona, Spain
| | - Olivia Boyer
- Pediatric Nephrology, Necker Hospital, APHP, MARHEA, Imagine Institute, Paris University, Paris, France
| | - Francesco Emma
- Division of Nephrology, Bambino Gesu Children's Hospital - IRCCS, Rome, Italy
| | - Roberta Camilla
- Nephrology, Dialysis, Transplantation, Regina Margherita University Hospital, Turin, Italy
| | - Pietro Manuel Ferraro
- U.O.S. Terapia Conservativa della Malattia Renale Cronica, U.O.C. Nefrologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy.,Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School Children's Hospital, Hannover, Germany
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital, Muenster, Germany
| | - Elena Levtchenko
- Division of Pediatric Nephrology, University Hospitals Leuven; Department of Development & Regeneration, Katholieke Universiteit Leuven, Belgium
| | - Sergio Camilo Lopez-Garcia
- Department of Renal Medicine, University College London, UK.,Renal Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Fernando Santos
- Department of Pediatrics, Hospital Universitario Central de Asturias and Área de Pediatría, Dpto. de Medicina, Universidad de Oviedo, Oviedo, Spain
| | - Stella Stabouli
- 1st Department of Pediatrics, Aristotle University, Thessaloniki, Greece
| | | | - Velibor Tasic
- University Children's Hospital, Medical School, Skopje, Macedonia
| | - Rezan Topaloglu
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Rosa Vargas-Poussou
- Department of Genetics, Centre de Références MARHEA, Hôpital Européen Georges Pompidou Assistance Publique Hôpitaux de Paris, Paris France
| | - Tanja Wlodkowski
- Department of Paediatric Nephrology, University Children's Hospital, Heidelberg, Germany
| | - Detlef Bockenhauer
- Department of General Pediatrics, University Children's Hospital, Muenster, Germany.,Division of Pediatric Nephrology, University Hospitals Leuven; Department of Development & Regeneration, Katholieke Universiteit Leuven, Belgium
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19
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Downie ML, Lopez Garcia SC, Kleta R, Bockenhauer D. Inherited Tubulopathies of the Kidney: Insights from Genetics. Clin J Am Soc Nephrol 2021; 16:620-630. [PMID: 32238367 PMCID: PMC8092065 DOI: 10.2215/cjn.14481119] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The kidney tubules provide homeostasis by maintaining the external milieu that is critical for proper cellular function. Without homeostasis, there would be no heartbeat, no muscle movement, no thought, sensation, or emotion. The task is achieved by an orchestra of proteins, directly or indirectly involved in the tubular transport of water and solutes. Inherited tubulopathies are characterized by impaired function of one or more of these specific transport molecules. The clinical consequences can range from isolated alterations in the concentration of specific solutes in blood or urine to serious and life-threatening disorders of homeostasis. In this review, we focus on genetic aspects of the tubulopathies and how genetic investigations and kidney physiology have crossfertilized each other and facilitated the identification of these disorders and their molecular basis. In turn, clinical investigations of genetically defined patients have shaped our understanding of kidney physiology.
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Affiliation(s)
- Mallory L. Downie
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Sergio C. Lopez Garcia
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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20
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Halbritter J. Genetics of kidney stone disease-Polygenic meets monogenic. Nephrol Ther 2021; 17S:S88-S94. [PMID: 33910705 DOI: 10.1016/j.nephro.2020.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 11/16/2022]
Abstract
Kidney stone disease comprising nephrolithiasis and nephrocalcinosis is a clinical syndrome of increasing prevalence with remarkable heterogeneity. Stone composition, age of manifestation, rate of recurrence, and impairment of kidney function varies with underlying etiologies. While calcium-based kidney stones account for the vast majority their etiology is still poorly understood. Recent studies underline the notion that genetic susceptibility together with dietary habits constitutes the major driver of kidney stone formation. In addition to single gene (Mendelian) disorders, which are most likely underestimated in the adult population, common risk alleles explain part of the observed heritability. Interestingly, identified GWAS loci often match those of Mendelian disease genes and vice versa (CASR, SLC34A1, CYP24A1). These findings provide mechanistic links related to renal calcium homeostasis, vitamin D metabolism, and CaSR-signaling regulated by the CaSR-CLDN14-CLDN16/19 axis (paracellular Ca2+ reabsorption) and TRPV5 (transcellular Ca2+ reabsorption). Recent identification of new single gene disorders of calcium-oxalate-nephrolithiasis (SLC26A1, CLDN2) and distal renal tubular acidosis with nephrocalcinosis (FOXI1, WDR72, ATP6V1C2) enabled additional insights into the kidney-gut axis and molecular prerequisites of proper urinary acidification. Implementation of centralized patient registries on hereditary kidney stone diseases are necessary to build up well characterized cohorts for urgently needed clinical studies.
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Affiliation(s)
- Jan Halbritter
- Medical Department III, Endocrinology, Nephrology and Rheumatology, Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany.
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21
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Fairweather SJ, Shah N, Brӧer S. Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 21:13-127. [PMID: 33052588 DOI: 10.1007/5584_2020_584] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H+ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost β uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b0,+AT-rBAT and the SLC6 family heteromer B0AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.
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Affiliation(s)
- Stephen J Fairweather
- Research School of Biology, Australian National University, Canberra, ACT, Australia. .,Resarch School of Chemistry, Australian National University, Canberra, ACT, Australia.
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Stefan Brӧer
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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22
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Atmis B, Cevizli D, Melek E, Bisgin A, Unal I, Anarat A, Bayazit AK. Evaluation of phenotypic and genotypic features of children with distal kidney tubular acidosis. Pediatr Nephrol 2020; 35:2297-2306. [PMID: 32613277 DOI: 10.1007/s00467-020-04685-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND The present study aimed to assess genotype-phenotype correlations with long-term prognosis in children with distal kidney tubular acidosis (dKTA). The kidney function of children with dKTA could be impaired in the long-term. METHODS Thirty-one children with dKTA from 23 families were included in the present study. Demographic features, growth parameters, clinical manifestations, follow-up results, and genetic analysis results of the patients were recorded. RESULTS Eighteen children (58.1%) were male. The median age at diagnosis was 3 months. The median follow-up period was 77 months and the longest was 23.5 years. Eight (28.8%) patients had chronic kidney disease (CKD) stage 2 or 3. Three patients aged 24, 23, and 19 years had CKD stage 3 with an estimated glomerular filtration rate of 54, 57, and 48 mL/min/1.73 m2, respectively. Thirteen patients had mutations in the ATP6V0A4 gene, eight had mutations in the ATP6V1B1 gene, and three had mutations in the SLC4A1 gene. There was no significant correlation between molecular diagnosis and CKD. Growth retardation with a height below a standard deviation (SD) score of - 2 was found in 14 patients (45.1%) at the time of diagnosis. The mean height SD score at the last visit was significantly higher in patients who had adequate metabolic control at > 75% of all visits as compared with that in patients who did not. CONCLUSION Patients with dKTA usually have a good clinical prognosis in childhood with appropriate treatment; however, dRTA is characterized by deterioration of kidney function in adulthood, particularly after puberty.
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Affiliation(s)
- Bahriye Atmis
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey.
| | - Derya Cevizli
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Engin Melek
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Atil Bisgin
- Department of Medical Genetics, Faculty of Medicine, Cukurova University, Adana, Turkey.,Cukurova University AGENTEM (Adana Genetic Diseases Diagnosis and Treatment Center), Adana, Turkey
| | - Ilker Unal
- Department of Biostatistics, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Ali Anarat
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Aysun K Bayazit
- Department of Pediatric Nephrology, Cukurova University Faculty of Medicine, Adana, Turkey
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23
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Sakuraya K, Nozu K, Oka I, Fujinaga S, Nagano C, Ohtomo Y, Iijima K. A different clinical manifestation in a Japanese family with autosomal dominant distal renal tubular acidosis caused by SLC4A1 mutation. CEN Case Rep 2020; 9:442-445. [DOI: 10.1007/s13730-020-00500-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/22/2020] [Indexed: 10/23/2022] Open
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24
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More TA, Kedar PS. Genotypic analysis of SLC4A1 A858D mutation in Indian population associated with distal renal tubular Acidosis (dRTA) coupled with hemolytic anemia. Gene 2020; 769:145241. [PMID: 33068675 DOI: 10.1016/j.gene.2020.145241] [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: 08/18/2020] [Revised: 09/27/2020] [Accepted: 10/11/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Although distinctive, distal renal tubular acidosis (dRTA) and Hereditary Spherocytosis (HS) shares a common protein, the anion exchanger1 (AE1) encoded by SLC4A1gene. In spite of this, the co-existence of dRTA and HS has rarely been observed. To date, 23 mutations have been identified in SLC4A1 gene causing both autosomal recessive (AR) and autosomal dominant (AD) forms of dRTA. METHODS We have assessed the applicability of the High Resolution Melting curve (HRM) method for the detection of SLC4A1 (A858D) mutation in 12 Indian families having AR dRTA coupled with HS. The reliability of the HRM analysis was verified by comparing the results of the HRM method with those of conventional methods such as Polymerase Chain Reaction-Restriction Fragment-Length Polymorphism (PCR-RFLP) and Sanger sequencing thereby confirming the diagnosis. RESULTS We here described the clinical, hematological and genetic data of 16 individuals from 12 families having AR dRTA coupled with HS. All patients carried homozygous SLC4A1 (A858D) mutation, whereas their family members had heterozygous A858D obtained by HRM analysis and confirmed by RFLP and Sanger sequencing. CONCLUSION Our data indicates that a missense mutation of A858D in SLC4A1 gene is the most common cause of dRTA coupled with HS in the Indian population. HRM analysis can be used as a rapid screening method for common SLC4A1 mutations that cause AR dRTA in the Indian population.
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Affiliation(s)
- Tejashree Anil More
- Department of Hematogenetics, ICMR-National Institute of Immunohematology, KEM Hospital Campus, Parel, Mumbai 40012, India
| | - Prabhakar S Kedar
- Department of Hematogenetics, ICMR-National Institute of Immunohematology, KEM Hospital Campus, Parel, Mumbai 40012, India.
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25
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Lopez-Garcia SC, Emma F, Walsh SB, Fila M, Hooman N, Zaniew M, Bertholet-Thomas A, Colussi G, Burgmaier K, Levtchenko E, Sharma J, Singhal J, Soliman NA, Ariceta G, Basu B, Murer L, Tasic V, Tsygin A, Decramer S, Gil-Peña H, Koster-Kamphuis L, La Scola C, Gellermann J, Konrad M, Lilien M, Francisco T, Tramma D, Trnka P, Yüksel S, Caruso MR, Chromek M, Ekinci Z, Gambaro G, Kari JA, König J, Taroni F, Thumfart J, Trepiccione F, Winding L, Wühl E, Ağbaş A, Belkevich A, Vargas-Poussou R, Blanchard A, Conti G, Boyer O, Dursun I, Pınarbaşı AS, Melek E, Miglinas M, Novo R, Mallett A, Milosevic D, Szczepanska M, Wente S, Cheong HI, Sinha R, Gucev Z, Dufek S, Iancu D, Kleta R, Schaefer F, Bockenhauer D. Treatment and long-term outcome in primary distal renal tubular acidosis. Nephrol Dial Transplant 2020; 34:981-991. [PMID: 30773598 DOI: 10.1093/ndt/gfy409] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Primary distal renal tubular acidosis (dRTA) is a rare disorder, and we aimed to gather data on treatment and long-term outcome. METHODS We contacted paediatric and adult nephrologists through European professional organizations. Responding clinicians entered demographic, biochemical, genetic and clinical data in an online form. RESULTS Adequate data were collected on 340 patients (29 countries, female 52%). Mutation testing had been performed on 206 patients (61%); pathogenic mutations were identified in 170 patients (83%). The median (range) presentation age was 0.5 (0-54) years and age at last follow-up was 11.0 (0-70.0) years. Adult height was slightly below average with a mean (SD score) of -0.57 (±1.16). There was an increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (35%) and adults (82%). Nephrocalcinosis was reported in 88%. Nephrolithiasis was more common with SLC4A1 mutations (42% versus 21%). Thirty-six percent had hearing loss, particularly in ATP6V1B1 (88%). The median (interquartile range) prescribed dose of alkali (mEq/kg/day) was 1.9 (1.2-3.3). Adequate metabolic control (normal plasma bicarbonate and normocalciuria) was achieved in 158 patients (51%), more commonly in countries with higher gross domestic product (67% versus 23%), and was associated with higher height and estimated glomerular filtration rate. CONCLUSION Long-term follow-up from this large dRTA cohort shows an overall favourable outcome with normal adult height for most and no patient with CKD Stage 5. However, 82% of adult patients have CKD Stages 2-4. Importance of adequate metabolic control was highlighted by better growth and renal function but was achieved in only half of patients.
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Affiliation(s)
- Sergio Camilo Lopez-Garcia
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
| | - Francesco Emma
- Division of Nephrology, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK
| | - Marc Fila
- Pediatric Nephrology-CHU Arnaud de Villeneuve, Montpellier University Hospital, Montpellier, France
| | - Nakysa Hooman
- Ali-Asghar Clinical Research Development Center, Iran University of Medical Sciences, Tehran, Iran
| | - Marcin Zaniew
- Department of Pediatrics, University of Zielona Góra, Zielona Góra, Poland
| | | | | | - Kathrin Burgmaier
- Department of Pediatrics, University Hospital of Cologne, Cologne, Germany
| | | | | | | | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Gema Ariceta
- Hospital Universitario Vall d'Hebron, Barcelona, Spain
| | - Biswanath Basu
- Division of Pediatric Nephrology, NRS Medical College, Kolkata, India
| | - Luisa Murer
- Pediatric Nephrology, Dialysis and Transplant Unit, Azienda Ospedaliera & University of Padova, Padova, Italy
| | - Velibor Tasic
- University Children's Hospital, Medical School, Skopje, Macedonia
| | - Alexey Tsygin
- National Medical and Research Centre for Children's Health, Moscow, Russia
| | - Stéphane Decramer
- Centre Hospitalier Universitaire de Toulouse, Service de Nephrologie Pediatrique, Hopital des Enfants, Centre De Reference des Maladies Rénales Rares du Sud Ouest, Toulouse, France
| | | | | | - Claudio La Scola
- Nephrology and Dialysis Unit, Department of Woman, Child and Urological Diseases, Azienda Ospedaliero-Universitaria Sant'Orsola-Malpighi, Bologna, Italy
| | | | | | - Marc Lilien
- Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
| | | | - Despoina Tramma
- Fourth Pediatric Department, Aristotle University, Thessaloniki, Greece
| | - Peter Trnka
- Lady Cilento Children's Hospital, Brisbane, Australia.,School of Medicine, the University of Queensland, Brisbane, Australia
| | - Selçuk Yüksel
- Department of Pediatric Nephrology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Maria Rosa Caruso
- Nephrology Unit Azienda Ospedaliera, Papa Giovani XXIII, Bergamo, Italy
| | | | - Zelal Ekinci
- Group Florence Nightingale Hospitals, İstanbul, Turkey
| | - Giovanni Gambaro
- Fondazione Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jens König
- University Children's Hospital, Münster, Germany
| | - Francesca Taroni
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "L. Vanvitelli", Naples, Italy
| | - Louise Winding
- Pediatric Department, Lillebaelt Hospital Kolding, Kolding, Denmark
| | - Elke Wühl
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University Hospital of Heidelberg, Heidelberg, Germany
| | - Ayşe Ağbaş
- Haseki Education and Research Hospital, Istanbul, Turkey
| | | | - Rosa Vargas-Poussou
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Anne Blanchard
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Giovanni Conti
- Pediatric Nephrology Unit, AOU Policlinic G Martino, Messina, Italy
| | | | - Ismail Dursun
- Faculty of Medicine, Department of Pediatric Nephrology, Erciyes University, Kayseri, Turkey
| | - Ayşe Seda Pınarbaşı
- Faculty of Medicine, Department of Pediatric Nephrology, Erciyes University, Kayseri, Turkey
| | | | - Marius Miglinas
- Nephrology Centre, Santaros Klinikos, Vilnius University, Vilnius, Lithuania
| | | | - Andrew Mallett
- School of Medicine, the University of Queensland, Brisbane, Australia.,Department of Renal Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | | | | | - Sarah Wente
- Department of Pediatric Nephrology, Hannover Medical School, Hannover, Germany
| | - Hae Il Cheong
- Department of Pediatrics, Seoul University Children's Hospital, Seoul, Korea
| | | | - Zoran Gucev
- Medical School, University Children's Hospital, Skopje, Macedonia
| | - Stephanie Dufek
- Centre for Nephrology, University College London, London, UK
| | - Daniela Iancu
- Centre for Nephrology, University College London, London, UK
| | | | - Robert Kleta
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
| | - Franz Schaefer
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University Hospital of Heidelberg, Heidelberg, Germany
| | - Detlef Bockenhauer
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
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26
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Bertocchio JP, Genetet S, Da Costa L, Walsh SB, Knebelmann B, Galimand J, Bessenay L, Guitton C, De Lafaille R, Vargas-Poussou R, Eladari D, Mouro-Chanteloup I. Red Blood Cell AE1/Band 3 Transports in Dominant Distal Renal Tubular Acidosis Patients. Kidney Int Rep 2020; 5:348-357. [PMID: 32154456 PMCID: PMC7056926 DOI: 10.1016/j.ekir.2019.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 11/26/2019] [Accepted: 12/31/2019] [Indexed: 11/30/2022] Open
Abstract
Introduction Anion exchanger 1 (AE1) (SLC4A1 gene product) is a membrane protein expressed in both kidney and red blood cells (RBCs): it exchanges extracellular bicarbonate (HCO3–) for intracellular chloride (Cl–) and participates in acid−base homeostasis. AE1 mutations in kidney α-intercalated cells can lead to distal renal tubular acidosis (dRTA). In RBC, AE1 (known as band 3) is also implicated in membrane stability: deletions can cause South Asian ovalocytosis (SAO). Methods We retrospectively collected clinical and biological data from patients harboring dRTA due to a SLC4A1 mutation and analyzed HCO3– and Cl– transports (by stopped-flow spectrophotometry) and expression (by flow cytometry, fluorescence activated cell sorting, and Coomassie blue staining) in RBCs, as well as RBC membrane stability (ektacytometry). Results Fifteen patients were included. All experience nephrolithiasis and/or nephrocalcinosis, 2 had SAO and dRTA (dRTA SAO+), 13 dominant dRTA (dRTA SAO−). The latter did not exert specific RBC membrane anomalies. Both HCO3– and Cl– transports were lower in patients with dRTA SAO+ than in those with dRTA SAO− or controls. Using 3 different extracellular probes, we report a decreased expression (by 52%, P < 0.05) in dRTA SAO+ patients by fluorescence activated cell sorting, whereas total amount of protein was not affected. Conclusion Band 3 transport function and expression in RBCs from dRTA SAO− patients is normal. However, in SAO RBCs, impaired conformation of AE1/band 3 corresponds to an impaired function. Thus, the driver of acid−base defect during dominant dRTA is probably an impaired membrane expression.
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Affiliation(s)
- Jean-Philippe Bertocchio
- Renal and Metabolic Diseases Unit, Assistance Publique-Hôpitaux de Paris, European Georges Pompidou Hospital, Paris, France.,Faculty of Medicine, Paris Descartes University, Paris, France.,Reference Center for Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Genito-urinary Medical Oncology and Research Department, MD Anderson Cancer Center, Houston, Texas, USA
| | - Sandrine Genetet
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,Team 1, Physiology of Normal and Pathologic Red Blood Cell, Institut National de la Transfusion Sanguine (INTS), Paris, France
| | - Lydie Da Costa
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,UMR_S1134, Inserm, Paris, France.,Service d'Hématologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Stephen B Walsh
- Department of Renal Medicine, University College of London, London, UK
| | - Bertrand Knebelmann
- Nephrology Department, Assistance Publique-Hôpitaux de Paris, Necker-Enfants Malades Hospital, Paris, France
| | - Julie Galimand
- Service d'Hématologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Lucie Bessenay
- Pediatrics Department, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Corinne Guitton
- Pediatrics Department, Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Renaud De Lafaille
- Nephrology Department, University Hospital of Bordeaux, Bordeaux, Aquitaine, France
| | - Rosa Vargas-Poussou
- Reference Center for Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Institut National pour la Santé et la Recherche Médicale (INSERM), Unité Mixte de Recherche UMRS1138, Cordeliers Research Center, Paris, France.,Genetics Department, Assistance Publique-Hôpitaux de Paris, European Georges Pompidou Hospital, Paris, France
| | - Dominique Eladari
- Renal and Metabolic Diseases Department, CHU de la Réunion, Felix Guyon Hospital, Saint Denis, France.,INSERM, UMRS 1283-European Genomic Institute for Diabetes, Lille, France
| | - Isabelle Mouro-Chanteloup
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,Team 1, Physiology of Normal and Pathologic Red Blood Cell, Institut National de la Transfusion Sanguine (INTS), Paris, France
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27
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Dahmani M, Talbi S, Ammar-Khodja F, Ouhab S, Boudjenah F, Djebbar M, Bonnet C, Petit C. ATP6V1B1 recurrent mutations in Algerian deaf patients associated with renal tubular acidosis. Int J Pediatr Otorhinolaryngol 2020; 129:109772. [PMID: 31733597 DOI: 10.1016/j.ijporl.2019.109772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/04/2019] [Accepted: 11/04/2019] [Indexed: 10/25/2022]
Abstract
Hereditary distal renal tubular acidosis (dRTA) is a rare disorder characterized by metabolic acidosis due to impaired renal acid excretion. To date, three genes (ATP6V1B1, ATP6V0A4 and SLC4A1) have been reported to be responsible for this genetic disorder. Notably, mutations of ATP6V1B1 gene, which encode B1-subunit of H + -ATPase pump cause distal renal tubular acidosis often, associated with sensorineural hearing loss (SNHL). Furthermore, enlarged vestibular aqueduct (EVA) was also described in some patients with ATP6V1B1 mutations. Four Algerian unrelated patients presented with dRTA and SNHL were recruited. The ATP6V1B1 gene was preferentially analyzed in all these patients by Sanger sequencing. We identified two previously reported variants in ATP6V1B1 gene: a frameshift mutation (c.1155dupC: p.(Ile386Hisfs*56) in exon 12 and a splicing mutation in intron 2 (c.175-1G > C: p?). Both mutations were homozygous in affected members. Interestingly, one patient with p.(Ile386Hisfs*56) mutation presented profound SNHL and bilateral enlarged vestibular aqueduct (EVA). Our study indicates the importance contribution of ATP6V1B1 gene mutations to the pathogenesis of the dRTA in the Algerian population and will contribute to introducing principles to predict the characteristics of the dRTA in patients. Thus, screening for this gene could allow rapid patient management and provide adequate genetic counseling.
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Affiliation(s)
- Malika Dahmani
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Siences et de La Technologie Houari Boumédiène (USTHB), Alger, Algeria.
| | - Sonia Talbi
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Siences et de La Technologie Houari Boumédiène (USTHB), Alger, Algeria
| | - Fatima Ammar-Khodja
- Equipe de Génétique, Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, Université des Siences et de La Technologie Houari Boumédiène (USTHB), Alger, Algeria
| | - Sofiane Ouhab
- Service D'Otorhinolaryngologie (ORL), Établissement Public Hospitalier Bachir Mentouri, Alger, Algeria
| | - Farid Boudjenah
- Service D'Otorhinolaryngologie (ORL), Centre Hospitalier Universitaire (CHU) de Tizi Ouzou, Algeria
| | - Merieme Djebbar
- Ecole des Sourds-muets (Villa La Chimère), Telemly, Alger, Algeria
| | - Crystel Bonnet
- Institut de La Vision, UMRS 1120 INSERM/UPMC. Paris 6, Paris, France
| | - Christine Petit
- Institut de La Vision, UMRS 1120 INSERM/UPMC. Paris 6, Paris, France; Institut Pasteur, Unité de Génétique et Physiologie de L'Audition, Paris, France; Collège de France, Paris, France
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Saccharomyces cerevisiae: First Steps to a Suitable Model System To Study the Function and Intracellular Transport of Human Kidney Anion Exchanger 1. mSphere 2020; 5:5/1/e00802-19. [PMID: 31996424 PMCID: PMC6992373 DOI: 10.1128/msphere.00802-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Distal renal tubular acidosis (dRTA) is a common kidney dysfunction characterized by impaired acid secretion via urine. Previous studies revealed that α-intercalated cells of dRTA patients express mutated forms of human kidney anion exchanger 1 (kAE1) which result in inefficient plasma membrane targeting or diminished expression levels of kAE1. However, the precise dRTA-causing processes are inadequately understood, and alternative model systems are helpful tools to address kAE1-related questions in a fast and inexpensive way. In contrast to a previous study, we successfully expressed full-length kAE1 in Saccharomyces cerevisiae. Using advanced microscopy techniques as well as different biochemical and functionality assays, plasma membrane localization and biological activity were confirmed for the heterologously expressed anion transporter. These findings represent first important steps to use the potential of yeast as a model organism for studying trafficking, activity, and degradation of kAE1 and its mutant variants in the future. Saccharomyces cerevisiae has been frequently used to study biogenesis, functionality, and intracellular transport of various renal proteins, including ion channels, solute transporters, and aquaporins. Specific mutations in genes encoding most of these renal proteins affect kidney function in such a way that various disease phenotypes ultimately occur. In this context, human kidney anion exchanger 1 (kAE1) represents an important bicarbonate/chloride exchanger which maintains the acid-base homeostasis in the human body. Malfunctions in kAE1 lead to a pathological phenotype known as distal renal tubular acidosis (dRTA). Here, we evaluated the potential of baker's yeast as a model system to investigate different cellular aspects of kAE1 physiology. For the first time, we successfully expressed yeast codon-optimized full-length versions of tagged and untagged wild-type kAE1 and demonstrated their partial localization at the yeast plasma membrane (PM). Finally, pH and chloride measurements further suggest biological activity of full-length kAE1, emphasizing the potential of S. cerevisiae as a model system for studying trafficking, activity, and/or degradation of mammalian ion channels and transporters such as kAE1 in the future. IMPORTANCE Distal renal tubular acidosis (dRTA) is a common kidney dysfunction characterized by impaired acid secretion via urine. Previous studies revealed that α-intercalated cells of dRTA patients express mutated forms of human kidney anion exchanger 1 (kAE1) which result in inefficient plasma membrane targeting or diminished expression levels of kAE1. However, the precise dRTA-causing processes are inadequately understood, and alternative model systems are helpful tools to address kAE1-related questions in a fast and inexpensive way. In contrast to a previous study, we successfully expressed full-length kAE1 in Saccharomyces cerevisiae. Using advanced microscopy techniques as well as different biochemical and functionality assays, plasma membrane localization and biological activity were confirmed for the heterologously expressed anion transporter. These findings represent first important steps to use the potential of yeast as a model organism for studying trafficking, activity, and degradation of kAE1 and its mutant variants in the future.
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Kyono Y, Nozu K, Nakagawa T, Takami Y, Fujita H, Ioroi T, Kugo M, Iijima K, Kamiyoshi N. Combination of furosemide and fludrocortisone as a loading test for diagnosis of distal renal tubular acidosis in a pediatric case. CEN Case Rep 2019; 9:81-86. [PMID: 31705302 DOI: 10.1007/s13730-019-00432-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/27/2019] [Indexed: 11/26/2022] Open
Abstract
Renal tubular acidosis (RTA) is a rare disease caused by a defect of urinary acidification. The ammonium chloride loading test is the gold standard method for determining the type of RTA. However, because this test has some side effects (e.g., nausea, vomiting, and stomach discomfort), applying this test for pediatric cases is difficult. Recently, a loading test with the combination of furosemide and fludrocortisone was reported to be an alternative to the ammonium chloride loading test, with 100% sensitivity and specificity in adult's cases. We report the first pediatric case of distal RTA in a patient who was successfully diagnosed by a drug loading test with the combination of furosemide and fludrocortisone without any side effects. We also performed genetic analysis and detected a known pathogenic variant in the SLC4A1 gene. The combination loading test of furosemide and fludrocortisone is a useful and safe diagnostic tool for pediatric cases of RTA.
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Affiliation(s)
- Yuki Kyono
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
| | - Taku Nakagawa
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Yuichi Takami
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Hideki Fujita
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Tomoaki Ioroi
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Masaaki Kugo
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
| | - Naohiro Kamiyoshi
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan.
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Jobst-Schwan T, Klämbt V, Tarsio M, Heneghan JF, Majmundar AJ, Shril S, Buerger F, Ottlewski I, Shmukler BE, Topaloglu R, Hashmi S, Hafeez F, Emma F, Greco M, Laube GF, Fathy HM, Pohl M, Gellermann J, Milosevic D, Baum MA, Mane S, Lifton RP, Kane PM, Alper SL, Hildebrandt F. Whole exome sequencing identified ATP6V1C2 as a novel candidate gene for recessive distal renal tubular acidosis. Kidney Int 2019; 97:567-579. [PMID: 31959358 DOI: 10.1016/j.kint.2019.09.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/08/2019] [Accepted: 09/12/2019] [Indexed: 12/18/2022]
Abstract
Distal renal tubular acidosis is a rare renal tubular disorder characterized by hyperchloremic metabolic acidosis and impaired urinary acidification. Mutations in three genes (ATP6V0A4, ATP6V1B1 and SLC4A1) constitute a monogenic causation in 58-70% of familial cases of distal renal tubular acidosis. Recently, mutations in FOXI1 have been identified as an additional cause. Therefore, we hypothesized that further monogenic causes of distal renal tubular acidosis remain to be discovered. Panel sequencing and/or whole exome sequencing was performed in a cohort of 17 families with 19 affected individuals with pediatric onset distal renal tubular acidosis. A causative mutation was detected in one of the three "classical" known distal renal tubular acidosis genes in 10 of 17 families. The seven unsolved families were then subjected to candidate whole exome sequencing analysis. Potential disease causing mutations in three genes were detected: ATP6V1C2, which encodes another kidney specific subunit of the V-type proton ATPase (1 family); WDR72 (2 families), previously implicated in V-ATPase trafficking in cells; and SLC4A2 (1 family), a paralog of the known distal renal tubular acidosis gene SLC4A1. Two of these mutations were assessed for deleteriousness through functional studies. Yeast growth assays for ATP6V1C2 revealed loss-of-function for the patient mutation, strongly supporting ATP6V1C2 as a novel distal renal tubular acidosis gene. Thus, we provided a molecular diagnosis in a known distal renal tubular acidosis gene in 10 of 17 families (59%) with this disease, identified mutations in ATP6V1C2 as a novel human candidate gene, and provided further evidence for phenotypic expansion in WDR72 mutations from amelogenesis imperfecta to distal renal tubular acidosis.
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Affiliation(s)
- Tilman Jobst-Schwan
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Verena Klämbt
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY
| | - John F Heneghan
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Amar J Majmundar
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shirlee Shril
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Florian Buerger
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Isabel Ottlewski
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Boris E Shmukler
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Rezan Topaloglu
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Seema Hashmi
- Department of Pediatric Nephrology, Sindh Institute of Urology and Transplantation, Karachi, Pakistan
| | - Farkhanda Hafeez
- Department of Pediatric Nephrology, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Francesco Emma
- Department of Pediatric Subspecialties, Division of Nephrology, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Marcella Greco
- Department of Pediatric Subspecialties, Division of Nephrology, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Guido F Laube
- Nephrology Unit, University Children's Hospital, Zürich, Switzerland
| | - Hanan M Fathy
- Pediatric Nephrology Unit, Alexandria Faculty of Medicine, University of Alexandria, Alexandria, Egypt
| | - Martin Pohl
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Jutta Gellermann
- Department of Pediatrics, University Children's Hospital of Berlin, University Hospital Berlin Charité, Berlin, Germany
| | - Danko Milosevic
- University of Zagreb School of Medicine, Zagreb University Hospital Center, Zagreb, Croatia
| | - Michelle A Baum
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA; Yale Center for Mendelian Genomics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA; Yale Center for Mendelian Genomics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, NY
| | - Seth L Alper
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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De Vecchis D, Reithmeier RAF, Kalli AC. Molecular Simulations of Intact Anion Exchanger 1 Reveal Specific Domain and Lipid Interactions. Biophys J 2019; 117:1364-1379. [PMID: 31540709 PMCID: PMC6818359 DOI: 10.1016/j.bpj.2019.08.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/30/2019] [Accepted: 08/22/2019] [Indexed: 12/23/2022] Open
Abstract
Anion exchanger 1 (AE1) is responsible for the exchange of bicarbonate and chloride across the erythrocyte plasma membrane. Human AE1 consists of a cytoplasmic and a membrane domain joined by a 33-residue flexible linker. Crystal structures of the individual domains have been determined, but the intact AE1 structure remains elusive. In this study, we use molecular dynamics simulations and modeling to build intact AE1 structures in a complex lipid bilayer that resembles the native erythrocyte plasma membrane. AE1 models were evaluated using available experimental data to provide an atomistic view of the interaction and dynamics of the cytoplasmic domain, the membrane domain, and the connecting linker in a complete model of AE1 in a lipid bilayer. Anionic lipids were found to interact strongly with AE1 at specific amino acid residues that are linked to diseases and blood group antigens. Cholesterol was found in the dimeric interface of AE1, suggesting that it may regulate subunit interactions and anion transport.
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Affiliation(s)
- Dario De Vecchis
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | | | - Antreas C Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.
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32
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Shibata S. Role of Pendrin in the Pathophysiology of Aldosterone-Induced Hypertension. Am J Hypertens 2019; 32:607-613. [PMID: 30982848 DOI: 10.1093/ajh/hpz054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 04/11/2019] [Indexed: 11/14/2022] Open
Abstract
The recent advances in genetics and molecular biology have resulted in the characterization of key components that critically regulate renal NaCl transport and blood pressure. Pendrin is a Cl-/HCO3- exchanger that is highly expressed in thyroid, inner ear, and kidney. In the kidney, it is selectively present at the apical membrane in non-α intercalated cells of the connecting tubules and cortical collecting duct. Besides its role in acid/base homeostasis, accumulating studies using various genetically modified animals have provided compelling evidence that pendrin regulates extracellular fluid volume and electrolyte balance at the downstream of aldosterone signaling. We have shown that angiotensin II and aldosterone cooperatively control pendrin abundance partly through mammalian target of rapamycin signaling and mineralocorticoid receptor dephosphorylation, which is necessary for the kidney to prevent extracellular fluid loss and electrolyte disturbances under physiologic perturbations. In line with the experimental observations, several clinical data indicated that the impaired pendrin function can cause fluid and electrolyte abnormalities in humans. The purpose of this review is to provide an update on the recent progress regarding the role of pendrin in fluid and electrolyte homeostasis, as well as in the pathophysiology of hypertension associated with mineralocorticoid receptor signaling.
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Affiliation(s)
- Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan
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33
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Lashhab R, Ullah AS, Cordat E. Renal collecting duct physiology and pathophysiology. Biochem Cell Biol 2019; 97:234-242. [DOI: 10.1139/bcb-2018-0192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Rawad Lashhab
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - A.K.M. Shahid Ullah
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Abstract
Renal tubular acidosis should be suspected in poorly thriving young children with hyperchloremic and hypokalemic normal anion gap metabolic acidosis, with/without syndromic features. Further workup is needed to determine the type of renal tubular acidosis and the presumed etiopathogenesis, which informs treatment choices and prognosis. The risk of nephrolithiasis and calcinosis is linked to the presence (proximal renal tubular acidosis, negligible stone risk) or absence (distal renal tubular acidosis, high stone risk) of urine citrate excretion. New formulations of slow-release alkali and potassium combination supplements are being tested that are expected to simplify treatment and lead to sustained acidosis correction.
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Affiliation(s)
- Robert Todd Alexander
- Department of Pediatrics and Physiology, Stollery Children's Hospital, 11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada
| | - Martin Bitzan
- Division of Nephrology, Department of Pediatrics, The Montreal Children's Hospital, McGill University Health Centre, Room B RC.6651, Montreal, Quebec H4A 3J1, Canada; Al Jalila Children's Hospital, Al Jadaf PO Box 7662, Dubai, UAE.
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Watanabe T. Improving outcomes for patients with distal renal tubular acidosis: recent advances and challenges ahead. PEDIATRIC HEALTH MEDICINE AND THERAPEUTICS 2018; 9:181-190. [PMID: 30588151 PMCID: PMC6296208 DOI: 10.2147/phmt.s174459] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal acidification due to a failure of type A intercalated cells (A-ICs) in the collecting tubule. dRTA is characterized by persistent hyperchloremia, a normal plasma anion gap, and the inability to maximally lower urinary pH in the presence of systemic metabolic acidosis. Common clinical features of dRTA include vomiting, failure to thrive, polyuria, hypercalciuria, hypocitraturia, nephrocalcinosis, nephrolithiasis, growth delay, and rickets. Mutations in genes encoding three distinct transport proteins in A-ICs have been identified as causes of dRTA, including the B1/ATP6V1B1 and a4/ATP6V0A4 subunits of the vacuolar-type H+-ATPase (H+-ATPase) and the chloride–bicarbonate exchanger AE1/SLC4A1. Homozygous or compound heterozygous mutations in ATP6V1B1 and ATP6V0A4 lead to autosomal recessive (AR) dRTA. dRTA caused by SLC4A1 mutations can occur with either autosomal dominant or AR transmission. Red blood cell abnormalities have been associated with AR dRTA due to SLC4A1 mutations, including hereditary spherocytosis, Southeast Asia ovalocytosis, and others. Some patients with dRTA exhibit atypical clinical features, including transient and reversible proximal tubular dysfunction and hyperammonemia. Incomplete dRTA presents with inadequate urinary acidification, but without spontaneous metabolic acidosis and recurrent urinary stones. Heterozygous mutations in the AE1 or H+-ATPase genes have recently been reported in patients with incomplete dRTA. Early and sufficient doses of alkali treatment are needed for patients with dRTA. Normalized serum bicarbonate, urinary calcium excretion, urinary low-molecular-weight protein levels, and growth rate are good markers of adherence to and/or efficacy of treatment. The prognosis of dRTA is generally good in patients with appropriate treatment. However, recent studies showed an increased frequency of chronic kidney disease (CKD) in patients with dRTA during long-term follow-up. The precise pathogenic mechanisms of CKD in patients with dRTA are unknown.
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Affiliation(s)
- Toru Watanabe
- Department of Pediatrics, Niigata City General Hospital, Niigata City 950-1197, Japan,
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36
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Nephrolithiasis secondary to inherited defects in the thick ascending loop of henle and connecting tubules. Urolithiasis 2018; 47:43-56. [PMID: 30460527 DOI: 10.1007/s00240-018-1097-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/08/2018] [Indexed: 12/19/2022]
Abstract
Twin and genealogy studies suggest a strong genetic component of nephrolithiasis. Likewise, urinary traits associated with renal stone formation were found to be highly heritable, even after adjustment for demographic, anthropometric and dietary covariates. Recent high-throughput sequencing projects of phenotypically well-defined cohorts of stone formers and large genome-wide association studies led to the discovery of many new genes associated with kidney stones. The spectrum ranges from infrequent but highly penetrant variants (mutations) causing mendelian forms of nephrolithiasis (monogenic traits) to common but phenotypically mild variants associated with nephrolithiasis (polygenic traits). About two-thirds of the genes currently known to be associated with nephrolithiasis code for membrane proteins or enzymes involved in renal tubular transport. The thick ascending limb of Henle and connecting tubules are of paramount importance for renal water and electrolyte handling, urinary concentration and maintenance of acid-base homeostasis. In most instances, pathogenic variants in genes involved in thick ascending limb of Henle and connecting tubule function result in phenotypically severe disease, frequently accompanied by nephrocalcinosis with progressive CKD and to a variable degree by nephrolithiasis. The aim of this article is to review the current knowledge on kidney stone disease associated with inherited defects in the thick ascending loop of Henle and the connecting tubules. We also highlight recent advances in the field of kidney stone genetics that have implications beyond rare disease, offering new insights into the most common type of kidney stone disease, i.e., idiopathic calcium stone disease.
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Zhang R, Wang C, Lang Y, Gao Y, Chen Z, Lu J, Zhao X, Shao L. Five Novel Mutations in Chinese Children with Primary Distal Renal Tubular Acidosis. Genet Test Mol Biomarkers 2018; 22:599-606. [PMID: 30256676 DOI: 10.1089/gtmb.2018.0057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ruixiao Zhang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, P.R. China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Cui Wang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, P.R. China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Yanhua Lang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, P.R. China
| | - Yanxia Gao
- Department of Nephrology, Qingdao Branch of Qilu Hospital of Shandong University, Qingdao, P.R. China
| | - Zeqing Chen
- Academy for Engineer and Technology, The Fudan University, Shanghai, P.R. China
| | - Jingru Lu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, P.R. China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Xiangzhong Zhao
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, P.R. China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, P.R. China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, P.R. China
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38
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Liu J, Shen Q, Li G, Zhai Y, Fang X, Xu H. Clinical and genetic analysis of distal renal tubular acidosis in three Chinese children. Ren Fail 2018; 40:520-526. [PMID: 30230413 PMCID: PMC6147104 DOI: 10.1080/0886022x.2018.1487858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Objective: Primary distal renal tubular acidosis (dRTA) is a rare genetic disease characterized by distal tubular dysfunction leading to metabolic acidosis and alkaline urine. Growth retardation is a major concern in these children. The disease is caused by defects in at least three genes (SLC4A1, ATP6V0A4, and ATP6V1B1) involved in urinary distal acidification. Several series of dRTA patients from different ethnic backgrounds have been genetically studied, but genetic studies regarding Chinese population is rare. Our aim was to investigate the clinical features and genetic basis of primary dRTA in Chinese children. Methods: Three unrelated patients with dRTA participated in our study. Next-generation sequencing was performed, and the findings were validated using the Sanger sequencing method. Results: All patients exhibited hyperchloraemic metabolic acidosis, abnormally high urine pH, hypokalemia, and nephrocalcinosis. Growth retardation was observed in all patients. During the follow-up (range 1–4 years), alkali replacement therapy corrected the systemic metabolic acidosis, and two patients demonstrated normal growth. rhGH therapy was administered to patient-3 at the age of 6 years, and his growth rate was significantly improved (growth velocity 9.6 cm/yr). In total, 5 mutations were identified in our cohort of three patients, and four mutations were novel. Conclusions: We report the clinical and molecular characteristics of dRTA patients from China. The four novel mutations detected in our study extend the spectrum of gene mutations associated with primary dRTA. Furthermore, our study confirms the effect of early treatment in improving growth for dRTA patient and provides insight into the effects of rhGH on dRTA patients who were diagnosed late and exhibiting a persistent growth delay despite appropriate therapy.
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Affiliation(s)
- Jiaojiao Liu
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
| | - Qian Shen
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
| | - Guomin Li
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
| | - Yihui Zhai
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
| | - Xiaoyan Fang
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
| | - Hong Xu
- a Department of Nephrology , Children's Hospital of Fudan University , Shanghai , China
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Alonso-Varela M, Gil-Peña H, Coto E, Gómez J, Rodríguez J, Rodríguez-Rubio E, Santos F. Distal renal tubular acidosis. Clinical manifestations in patients with different underlying gene mutations. Pediatr Nephrol 2018; 33:1523-1529. [PMID: 29725771 DOI: 10.1007/s00467-018-3965-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/28/2018] [Accepted: 04/06/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND To evaluate whether there are differences in the phenotype of primary distal renal tubular acidosis (dRTA) patients according to the causal defective gene. METHODS Twenty-seven non-oriental patients with genetically confirmed dRTA were grouped according to the identified underlying mutations in either ATP6V1B1 (n = 10), ATP6V0A4 (n = 12), or SLC4A1 (n = 5) gene. Demographic features, growth impairment, biochemical variables and presence of deafness, nephrocalcinosis, and urolithiasis at diagnosis were compared among the three groups. RESULTS Patients with SLC4A1 mutations presented later than those with ATP6V1B1 or ATP6V0A4 defects (120 vs. 7 and 3 months, respectively). Hearing loss at diagnosis was present in the majority of patients with ATP6V1B1 mutations, in two patients with ATP6V0A4 mutations, and in none of cases harboring SLC4A1 mutations. Serum potassium concentration (X ± SD) was higher in SLC4A1 group (3.66 ± 0.44 mEq/L) than in ATP6V0A4 group (2.96 ± 0.63 mEq/L) (p = 0.046). There were no differences in the other clinical or biochemical variables analyzed in the three groups. CONCLUSIONS This study indicates that non-oriental patients with dRTA caused by mutations in the SLC4A1 gene present later and have normokalemia or milder hypokalemia. Hypoacusia at diagnosis is characteristically associated with ATP6V1B1 gene mutations although it may also be present in infants with ATP6V0A4 defects. Other phenotypical manifestations do not allow predicting the involved gene.
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Affiliation(s)
| | - Helena Gil-Peña
- University of Oviedo, Oviedo, Spain. .,AGC de Pediatría, Hospital Universitario Central de Asturias, 33011, Oviedo, Spain. .,Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain.
| | - Eliecer Coto
- University of Oviedo, Oviedo, Spain.,Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain.,AGC Laboratorio - Genética, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Juan Gómez
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain.,AGC Laboratorio - Genética, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Julián Rodríguez
- University of Oviedo, Oviedo, Spain.,AGC de Pediatría, Hospital Universitario Central de Asturias, 33011, Oviedo, Spain.,Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
| | | | - Fernando Santos
- University of Oviedo, Oviedo, Spain.,AGC de Pediatría, Hospital Universitario Central de Asturias, 33011, Oviedo, Spain.,Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
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40
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Deejai N, Wisanuyotin S, Nettuwakul C, Khositseth S, Sawasdee N, Saetai K, Yenchitsomanus PT, Rungroj N. Molecular Diagnosis of Solute Carrier Family 4 Member 1 (SLC4A1) Mutation–Related Autosomal Recessive Distal Renal Tubular Acidosis. Lab Med 2018; 50:78-86. [DOI: 10.1093/labmed/lmy051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nipaporn Deejai
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Suwannee Wisanuyotin
- Division of Nephrology, Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Thailand
| | - Choochai Nettuwakul
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Sookkasem Khositseth
- Division of Nephrology, Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathum Thani, Thailand
| | - Nunghathai Sawasdee
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Kiattichai Saetai
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Pa-thai Yenchitsomanus
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nanyawan Rungroj
- Division of Molecular Genetics, Department of Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
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41
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Abstract
Distal renal tubular acidosis (DRTA) is defined as hyperchloremic, non-anion gap metabolic acidosis with impaired urinary acid excretion in the presence of a normal or moderately reduced glomerular filtration rate. Failure in urinary acid excretion results from reduced H+ secretion by intercalated cells in the distal nephron. This results in decreased excretion of NH4+ and other acids collectively referred as titratable acids while urine pH is typically above 5.5 in the face of systemic acidosis. The clinical phenotype in patients with DRTA is characterized by stunted growth with bone abnormalities in children as well as nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria, hypocitraturia, and relatively alkaline urine. Hypokalemia is a striking finding that accounts for muscle weakness and requires continued treatment together with alkali-based therapies. This review will focus on the mechanisms responsible for impaired acid excretion and urinary potassium wastage, the clinical features, and diagnostic approaches of hypokalemic DRTA, both inherited and acquired.
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42
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Batlle D, Arruda J. Hyperkalemic Forms of Renal Tubular Acidosis: Clinical and Pathophysiological Aspects. Adv Chronic Kidney Dis 2018; 25:321-333. [PMID: 30139459 DOI: 10.1053/j.ackd.2018.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In contrast to distal type I or classic renal tubular acidosis (RTA) that is associated with hypokalemia, hyperkalemic forms of RTA also occur usually in the setting of mild-to-moderate CKD. Two pathogenic types of hyperkalemic metabolic acidosis are frequently encountered in adults with underlying CKD. One type, which corresponds to some extent to the animal model of selective aldosterone deficiency (SAD) created experimentally by adrenalectomy and glucocorticoid replacement, is manifested in humans by low plasma and urinary aldosterone levels, reduced ammonium excretion, and preserved ability to lower urine pH below 5.5. This type of hyperkalemic RTA is also referred to as type IV RTA. It should be noted that the mere deficiency of aldosterone when glomerular filtration rate is completely normal only causes a modest decline in plasma bicarbonate which emphasizes the importance of reduced glomerular filtration rate in the development of the hyperchloremic metabolic acidosis associated with SAD. Another type of hyperkalemic RTA distinctive from SAD in which plasma aldosterone is not reduced is referred to as hyperkalemic distal renal tubular acidosis because urine pH cannot be reduced despite acidemia or after provocative tests aimed at increasing sodium-dependent distal acidification such as the administration of sodium sulfate or loop diuretics with or without concurrent mineralocorticoid administration. This type of hyperkalemic RTA (also referred to as voltage-dependent distal renal tubular acidosis) has been best described in patients with obstructive uropathy and resembles the impairment in both hydrogen ion and potassium secretion that are induced experimentally by urinary tract obstruction and when sodium transport in the cortical collecting tubule is blocked by amiloride.
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43
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Zhou F, Mao J, Ye Q, Zhu X, Zhang Y, Ye Y, Fu H, Shen H, Lu Z, Xia Y, Liu A, Shu Q, Du L. Clinical features and genetic findings in Chinese children with distal renal tubular acidosis. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2018; 11:3523-3532. [PMID: 31949730 PMCID: PMC6962865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 04/28/2018] [Indexed: 06/10/2023]
Abstract
Distal renal tubular acidosis (dRTA) is characterized by metabolic acidosis due to uric acid dysfunction. The aim of this study was to demonstrate the genetic diagnosis of Chinese children with dRTA by whole-exome sequencing. From Jan. 2010 to Sept. 2015, 16 children with dRTA were recruited to investigate the possibility of genetic diagnosis and to examine any genotype-phenotype relationships in these patients. Sanger sequencing was used to confirm mutations identified by whole-exome sequencing. Clinical and biological features in the patients included hyperchloremic metabolic acidosis, impaired growth, hypokalemia, nephrocalcinosis, nephrolithiasis, hypercalciuria, hypocitraturia, and rickets or osteomalacia. Seventeen mutations in the solute carrier family 4 member 1 (SLC4A1), ATPase H+ transporting V0 subunit a4 (ATP6V0A4), ATPase H+ transporting V1 subunit B1 (ATP6V1B1), WNK lysine deficient protein kinase 1 (WNK1) and the claudin 16 (CLDN16) were identified in 15 patients, and 14 of these mutations are novel. Only 1 patient was negative for any mutations. Our results demonstrate the existence of SLC4A1, ATP6V1B1, ATP6V0A4, WNK1 and CLDN16 mutations in Chinese children with dRTA and indicate that compound heterozygosity at 2 or more different but related genes can be responsible for its pathogenesis. This study also indicates that whole-exome sequencing is a labor and cost-effective means of analyzing dRTA-associated genes.
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Affiliation(s)
- Fang Zhou
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
- Department of Internal Medicine, Hangzhou Children’s HospitalHangzhou, Zhejiang Province, China
| | - Jianhua Mao
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Qing Ye
- Department of Zhejiang Key Laboratory for Neonatal Diseases, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Xiujuan Zhu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Yingying Zhang
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Yuhong Ye
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Haidong Fu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Huijun Shen
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Zhihong Lu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Yonghui Xia
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Aimin Liu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Qiang Shu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
| | - Lizhong Du
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of MedicineHangzhou, Zhejiang Province, China
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44
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Kurtz I. Renal Tubular Acidosis: H +/Base and Ammonia Transport Abnormalities and Clinical Syndromes. Adv Chronic Kidney Dis 2018; 25:334-350. [PMID: 30139460 PMCID: PMC6128697 DOI: 10.1053/j.ackd.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
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45
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Rahmati N, Hoebeek FE, Peter S, De Zeeuw CI. Chloride Homeostasis in Neurons With Special Emphasis on the Olivocerebellar System: Differential Roles for Transporters and Channels. Front Cell Neurosci 2018; 12:101. [PMID: 29765304 PMCID: PMC5938380 DOI: 10.3389/fncel.2018.00101] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Abstract
The intraneuronal ionic composition is an important determinant of brain functioning. There is growing evidence that aberrant homeostasis of the intracellular concentration of Cl- ([Cl-]i) evokes, in addition to that of Na+ and Ca2+, robust impairments of neuronal excitability and neurotransmission and thereby neurological conditions. More specifically, understanding the mechanisms underlying regulation of [Cl-]i is crucial for deciphering the variability in GABAergic and glycinergic signaling of neurons, in both health and disease. The homeostatic level of [Cl-]i is determined by various regulatory mechanisms, including those mediated by plasma membrane Cl- channels and transporters. This review focuses on the latest advances in identification, regulation and characterization of Cl- channels and transporters that modulate neuronal excitability and cell volume. By putting special emphasis on neurons of the olivocerebellar system, we establish that Cl- channels and transporters play an indispensable role in determining their [Cl-]i and thereby their function in sensorimotor coordination.
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Affiliation(s)
- Negah Rahmati
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- NIDOD Institute, Wilhelmina Children's Hospital, University Medical Center Utrecht and Brain Center Rudolf Magnus, Utrecht, Netherlands
| | - Saša Peter
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
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46
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Exome sequencing confirms molecular diagnoses in 38 Chinese families with hereditary spherocytosis. SCIENCE CHINA-LIFE SCIENCES 2018; 61:947-953. [PMID: 29572776 DOI: 10.1007/s11427-017-9232-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 12/28/2017] [Indexed: 12/24/2022]
Abstract
Hereditary spherocytosis (HS), the most common cause of congenital hemolytic anemia, is caused by deficiency of the erythrocyte membrane proteins. Five causative genes (ANK1, SPTB, SPTA1, SLC4A1, and EPB42) have been identified. To date, molecular genetic studies have been performed in different populations, including the American, European, Brazilian, Japanese and Korean populations, whereas only a few studies have been described in the Chinese population. Here, by reanalysis of the exome data, we revealed causative mutations and established a definitive diagnosis of HS in all 38 Chinese families. We found 34 novel mutations and four reported mutations in three known HS-causing genes-17 in ANK1, 17 in SPTB and four in SLC4A1, suggesting that ANK1 and SPTB are the major genes in Chinese patients with HS. All of the ANK1 or SPTB mutations, scattered throughout the entire genes, are non-recurrent; and most of them are null mutations, which might cause HS via a haploinsufficiency mechanism. De novo mutations in ANK1 or SPTB often occur with an unexpected high frequency (87.5% and 64.2%, respectively). Our study updates our knowledge about the genetic profile of HS in Chinese and shows that family-based, especially parent-offspring trio, sequencing analysis can help to increase the diagnostic power and improve diagnostic efficiency.
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47
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Parker MD. Mouse models of SLC4-linked disorders of HCO 3--transporter dysfunction. Am J Physiol Cell Physiol 2018; 314:C569-C588. [PMID: 29384695 DOI: 10.1152/ajpcell.00301.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The SLC4 family Cl-/[Formula: see text] cotransporters (NBCe1, NBCe2, NBCn1, and NBCn2) contribute to a variety of vital physiological processes including pH regulation and epithelial fluid secretion. Accordingly, their dysfunction can have devastating effects. Disorders such as epilepsy, hemolytic anemia, glaucoma, hearing loss, osteopetrosis, and renal tubular acidosis are all genetically linked to SLC4-family gene loci. This review summarizes how studies of Slc4-modified mice have enhanced our understanding of the etiology of SLC4-linked pathologies and the interpretation of genetic linkage studies. The review also surveys the novel disease signs exhibited by Slc4-modified mice which could either be considered to presage their description in humans, or to highlight interspecific differences. Finally, novel Slc4-modified mouse models are proposed, the study of which may further our understanding of the basis and treatment of SLC4-linked disorders of [Formula: see text]-transporter dysfunction.
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Affiliation(s)
- Mark D Parker
- Department of Physiology and Biophysics, The State University of New York: The University at Buffalo , Buffalo, New York.,Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo: The State University of New York , Buffalo, New York.,State University of New York Eye Institutes, University at Buffalo: The State University of New York , Buffalo, New York
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48
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Halbritter J, Seidel A, Müller L, Schönauer R, Hoppe B. Update on Hereditary Kidney Stone Disease and Introduction of a New Clinical Patient Registry in Germany. Front Pediatr 2018; 6:47. [PMID: 29564324 PMCID: PMC5850730 DOI: 10.3389/fped.2018.00047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/19/2018] [Indexed: 12/15/2022] Open
Abstract
Kidney stone disease is an increasingly prevalent condition with remarkable clinical heterogeneity, with regards to stone composition, age of manifestation, rate of recurrence, and impairment of kidney function. Calcium-based kidney stones account for the vast majority of cases, but their etiology is poorly understood, notably their genetic drivers. As recent studies indicate, hereditary conditions are most likely underestimated in prevalence, and new disease genes are constantly being identified. As a consequence, there is an urgent need of a more efficient documentation and collection of cases with underlying hereditary conditions, to better understand shared phenotypic presentation and common molecular mechanisms. By implementation of a centralized patient registry on hereditary kidney stone disease in Germany, we aim to help closing the vast knowledge gap on genetics of kidney stone disease. In this context, clinical registries are indispensable for several reasons: first, delineating better phenotype-genotype associations will allow more precise patient stratification in future clinical research studies. Second, identifying new disease genes and new mechanisms will further reduce the rate of unknown nephrolithiasis/nephrocalcinosis etiology; and third, deciphering new molecular targets will pave the way to develop drugs for recurrence prevention in severely affected families.
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Affiliation(s)
- Jan Halbritter
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Anna Seidel
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Luise Müller
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Ria Schönauer
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Bernd Hoppe
- Division of Pediatric Nephrology, University Children's Hospital, Bonn, Germany
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49
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Enerbäck S, Nilsson D, Edwards N, Heglind M, Alkanderi S, Ashton E, Deeb A, Kokash FEB, Bakhsh ARA, Van't Hoff W, Walsh SB, D'Arco F, Daryadel A, Bourgeois S, Wagner CA, Kleta R, Bockenhauer D, Sayer JA. Acidosis and Deafness in Patients with Recessive Mutations in FOXI1. J Am Soc Nephrol 2017; 29:1041-1048. [PMID: 29242249 DOI: 10.1681/asn.2017080840] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 11/15/2017] [Indexed: 11/03/2022] Open
Abstract
Maintenance of the composition of inner ear fluid and regulation of electrolytes and acid-base homeostasis in the collecting duct system of the kidney require an overlapping set of membrane transport proteins regulated by the forkhead transcription factor FOXI1. In two unrelated consanguineous families, we identified three patients with novel homozygous missense mutations in FOXI1 (p.L146F and p.R213P) predicted to affect the highly conserved DNA binding domain. Patients presented with early-onset sensorineural deafness and distal renal tubular acidosis. In cultured cells, the mutations reduced the DNA binding affinity of FOXI1, which hence, failed to adequately activate genes crucial for normal inner ear function and acid-base regulation in the kidney. A substantial proportion of patients with a clinical diagnosis of inherited distal renal tubular acidosis has no identified causative mutations in currently known disease genes. Our data suggest that recessive mutations in FOXI1 can explain the disease in a subset of these patients.
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Affiliation(s)
- Sven Enerbäck
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden;
| | - Daniel Nilsson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Noel Edwards
- Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Mikael Heglind
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Sumaya Alkanderi
- Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Emma Ashton
- North East Thames Regional Genetic Service Laboratories, London, United Kingdom
| | - Asma Deeb
- Pediatric Services, Mafraq Hospital, Abu Dhabi, United Arab Emirates
| | - Feras E B Kokash
- College of Medicine, Gulf Medical University, Ajman, United Arab Emirates
| | - Abdul R A Bakhsh
- College of Medicine, Gulf Medical University, Ajman, United Arab Emirates
| | - William Van't Hoff
- Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London, United Kingdom
| | - Stephen B Walsh
- University College London Centre for Nephrology, London, United Kingdom
| | - Felice D'Arco
- College of Medicine, Gulf Medical University, Ajman, United Arab Emirates
| | - Arezoo Daryadel
- Institute of Physiology, University of Zürich, Zurich, Switzerland; and.,National Center for Competence in Research, National Center in Competence in Research Kidney.CH, Zurich, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zürich, Zurich, Switzerland; and.,National Center for Competence in Research, National Center in Competence in Research Kidney.CH, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zürich, Zurich, Switzerland; and.,National Center for Competence in Research, National Center in Competence in Research Kidney.CH, Zurich, Switzerland
| | - Robert Kleta
- Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London, United Kingdom.,University College London Centre for Nephrology, London, United Kingdom
| | - Detlef Bockenhauer
- Great Ormond Street Hospital for Children, National Health Service Foundation Trust, London, United Kingdom.,University College London Centre for Nephrology, London, United Kingdom
| | - John A Sayer
- Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, United Kingdom
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50
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Ficici E, Faraldo-Gómez JD, Jennings ML, Forrest LR. Asymmetry of inverted-topology repeats in the AE1 anion exchanger suggests an elevator-like mechanism. J Gen Physiol 2017; 149:1149-1164. [PMID: 29167180 PMCID: PMC5715908 DOI: 10.1085/jgp.201711836] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/10/2017] [Indexed: 12/02/2022] Open
Abstract
Anion exchanger 1 catalyzes the transmembrane antiport of chloride and bicarbonate ions through a mechanism that has remained unclear. By modeling its inward-facing state and comparing it with the known outward-facing form, Ficici et al. hypothesize that this transporter features an elevator-like mechanism. The membrane transporter anion exchanger 1 (AE1), or band 3, is a key component in the processes of carbon-dioxide transport in the blood and urinary acidification in the renal collecting duct. In both erythrocytes and the basolateral membrane of the collecting-duct α-intercalated cells, the role of AE1 is to catalyze a one-for-one exchange of chloride for bicarbonate. After decades of biochemical and functional studies, the structure of the transmembrane region of AE1, which catalyzes the anion-exchange reaction, has finally been determined. Each protomer of the AE1 dimer comprises two repeats with inverted transmembrane topologies, but the structures of these repeats differ. This asymmetry causes the putative substrate-binding site to be exposed only to the extracellular space, consistent with the expectation that anion exchange occurs via an alternating-access mechanism. Here, we hypothesize that the unknown, inward-facing conformation results from inversion of this asymmetry, and we propose a model of this state constructed using repeat-swap homology modeling. By comparing this inward-facing model with the outward-facing experimental structure, we predict that the mechanism of AE1 involves an elevator-like motion of the substrate-binding domain relative to the nearly stationary dimerization domain and to the membrane plane. This hypothesis is in qualitative agreement with a wide range of biochemical and functional data, which we review in detail, and suggests new avenues of experimentation.
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Affiliation(s)
- Emel Ficici
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Michael L Jennings
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Lucy R Forrest
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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