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Culver SA, Suleman N, Kavuru V, Siragy HM. Renal Hypokalemia: An Endocrine Perspective. J Clin Endocrinol Metab 2024; 109:1694-1706. [PMID: 38546505 DOI: 10.1210/clinem/dgae201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Indexed: 06/18/2024]
Abstract
The majority of disorders that cause renal potassium wasting present with abnormalities in adrenal hormone secretion. While these findings frequently lead patients to seek endocrine evaluation, clinicians often struggle to accurately diagnose these conditions, delaying treatment and adversely impacting patient care. At the same time, growing insight into the genetic and molecular basis of these disorders continues to improve their diagnosis and management. In this review, we outline a practical integrated approach to the evaluation of renal hypokalemia syndromes that are seen in endocrine practice while highlighting recent advances in understanding of the genetics and pathophysiology behind them.
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Affiliation(s)
- Silas A Culver
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Nawar Suleman
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Varun Kavuru
- Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Helmy M Siragy
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
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Nojehdeh ST, Mojbafan M, Hooman N, Hoseini R, Otukesh H. Genetic diagnosis of Bartter syndrome in Iranian patients and detection of a novel homozygous CLCNKB mutation. Clin Case Rep 2022; 10:e6698. [PMID: 36514463 PMCID: PMC9734084 DOI: 10.1002/ccr3.6698] [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: 04/08/2022] [Revised: 10/28/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
An Iranian girl with clinical symptoms of Bartter syndrome like hypokalemia, polyuria, polydipsia, hyponatremia, and hypochloremic alkalosis was referred to us in whom the CLCNKB gene was genetically evaluated using Sanger sequencing. A homozygous pathogenic variant of c.1332_1335delCTCT was detected in this patient.
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Affiliation(s)
| | - Marzieh Mojbafan
- Department of Medical Genetics, School of MedicineIran University of Medical Sciences (IUMS)TehranIran,Department of Medical GeneticsAli‐Asghar Children's HospitalTehranIran
| | - Nakysa Hooman
- Clinical research Development CenterIran University of Medical SciencesTehranIran,Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
| | - Rozita Hoseini
- Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
| | - Hasan Otukesh
- Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
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Yıldız G, Torun Bayram M, Çinleti T, Koç A, Soylu A, Kavukçu S. Late onset Bartter syndrome: Bartter syndrome type 2 presenting with isolated nephrocalcinosis and high parathyroid hormone levels mimicking primary hyperparathyroidism. J Pediatr Endocrinol Metab 2022; 35:1298-1301. [PMID: 35952717 DOI: 10.1515/jpem-2022-0154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/24/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Nephrocalcinosis is associated with conditions that cause hypercalcemia and the increased urinary excretion of calcium, phosphate, and/or oxalate. A monogenic etiology is found in almost 30% of childhood-onset nephrocalcinosis which is also a common manifestation of primary hyperparathyroidism. We discuss a child with nephrocalcinosis and features mimicking primary hyperparathyroidism. CASE PRESENTATION A 7-year-old girl presented with nephrocalcinosis. Hypercalciuria, hyperphosphaturia, mild hypercalcemia, hypophosphatemia and elevated parathyroid hormone levels along with normal serum creatinine and absence of hypokalemic alkalosis suggested primary hyperparathyroidism. However, she was ultimately diagnosed with Bartter syndrome type 2 based on the presence of homozygous pathogenic variation in KCNJ1gene. CONCLUSIONS This is the second reported case of late-onset Bartter syndrome type 2 without hypokalemic alkalosis. Patients with Bartter syndrome may present with high parathyroid hormone levels and hypercalcemia in addition to hypercalciuria. Thus, the present case suggests that the KCNJ1 gene should be included in genetic analysis even in older children with isolated nephrocalcinosis.
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Affiliation(s)
- Gizem Yıldız
- Department of Pediatric Nephrology, Dokuz Eylül University Medical Faculty, Izmir, Turkey
| | - Meral Torun Bayram
- Department of Pediatric Nephrology, Dokuz Eylül University Medical Faculty, Izmir, Turkey
| | - Tayfun Çinleti
- Department of Pediatric Genetic, Dokuz Eylül University Medical Faculty, Izmir, Turkey
| | - Altuğ Koç
- Department of Medical Genetics, Dokuz Eylül University Medical Faculty, Izmir, Turkey
| | - Alper Soylu
- Department of Pediatric Nephrology and Rheumatology, Dokuz Eylül University Medical Faculty, Izmir, Turkey
| | - Salih Kavukçu
- Department of Pediatric Nephrology and Rheumatology, Dokuz Eylül University Medical Faculty, Izmir, Turkey
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Tian M, Peng H, Bi X, Wang YQ, Zhang YZ, Wu Y, Zhang BR. Late-Onset Bartter Syndrome Type II Due to a Novel Compound Heterozygous Mutation in KCNJ1 Gene: A Case Report and Literature Review. Front Med (Lausanne) 2022; 9:862514. [PMID: 35463019 PMCID: PMC9021870 DOI: 10.3389/fmed.2022.862514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/14/2022] [Indexed: 11/16/2022] Open
Abstract
Background Bartter syndrome (BS) type II is a rare autosomal recessive renal tubular disorder caused by mutations in the KCNJ1 gene, which encodes the apical renal outer medullary potassium (ROMK) channel in the thick ascending limb (TAL) of Henle’s loop. BS type II is typically considered as a disorder of infancy and seldom seen in adults. Case Presentation A 34-year-old woman was admitted with generalized body numbness and hand convulsions, without growth retardation. Laboratory tests revealed hypokalemic metabolic alkalosis, hyperreninemic hyperaldosteronism, and nephrocalcinosis. She was misdiagnosed during the initial diagnosis process and was finally diagnosed with late-onset BS type II via genetic testing through next-generation sequencing combined with Sanger sequencing. A novel compound heterozygous p.Leu207Ile/p. Cys308Arg variant in exon 5 of the KCNJ1 gene from her parents was identified and speculated to be a potential pathogenic gene variation. Conclusion We report a case of late-onset BS type II with a novel compound heterozygous mutation in KCNJ1. Both variants are novel and have never been reported. Our report will have a significant impact on the diagnosis of BS in other patients without typical clinical presentations and emphasizes the importance of genetic investigation.
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Affiliation(s)
- Mi Tian
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Hui Peng
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xin Bi
- Guangzhou KingMed Center for Clinical Laboratory Co, Ltd., Guangzhou, China
| | - Yan-Qiu Wang
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yong-Zhe Zhang
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yan Wu
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Bei-Ru Zhang
- Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, China
- *Correspondence: Bei-Ru Zhang,
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Mani S, Nair J, Handa D. Antenatal Bartter syndrome: a new compound heterozygous mutation in exon 2 of KCNJ1 gene. BMJ Case Rep 2021; 14:e244685. [PMID: 34663630 PMCID: PMC8524263 DOI: 10.1136/bcr-2021-244685] [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] [Accepted: 08/22/2021] [Indexed: 11/03/2022] Open
Abstract
A 30+6/7-week infant was born by vaginal delivery to a 21-year-old primigravida with pregnancy complicated by polyhydramnios. The infant developed polyuria and significant weight loss in the first 2 weeks of life despite appropriate fluid management. He developed hyponatraemia, hypochloraemia, transient hyperkalaemia and prerenal azotaemia with metabolic acidosis. On further evaluation, he had elevated plasma renin and aldosterone levels. Bartter syndrome was considered in the differential diagnosis. Bartter syndrome gene panel revealed a rare compound heterozygous mutation in exon 2 of the KCNJ1 gene (Lys186Glu/Thr71Met), suggesting antenatal Bartter syndrome (type 2). The infant developed late-onset hypokalaemia and metabolic alkalosis by week 4 of life. He regained birth weight by week 3 of life but failed to thrive (10-20 g/kg/day) despite high caloric intake (140 kcal/kg/day). His electrolyte abnormalities gradually improved, and he was discharged home without the need for electrolyte supplements or medications.
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Affiliation(s)
- Srinivasan Mani
- Pediatrics, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA
| | - Jayasree Nair
- Pediatrics, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA
| | - Deepali Handa
- Pediatrics, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York, USA
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Saleem N, Nasir H, Hassan D, Manzoor M. Association of Adult-Onset Bartter Syndrome With Undifferentiated Connective Tissue Disorder. Cureus 2021; 13:e17140. [PMID: 34532176 PMCID: PMC8435068 DOI: 10.7759/cureus.17140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2021] [Indexed: 01/17/2023] Open
Abstract
Bartter syndrome is a rare autosomal recessive, salt-losing disorder characterized by hypokalemic hypochloremic metabolic alkalosis. We are reporting a case of 21 years old patient, who presented with lower limb weakness, marked hypokalemia, proteinuria, and renal impairment detected on laboratory evaluation. The diagnosis of Bartter syndrome was suspected by marked hypokalemia and was supported by renal biopsy which showed evidence of Juxtaglomerular (JG) hyperplasia. This is the first case report about clinicopathological features of the patient with acquired Bartter syndrome and associated undifferentiated connective tissue disorder manifesting as hypokalemia with paralysis.
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Affiliation(s)
- Nida Saleem
- Internal Medicine/Nephrology, Shifa International Hospital, Islamabad, PAK
| | - Humaira Nasir
- Histopathology, Shifa International Hospital, Islamabad, PAK
| | - Danyal Hassan
- Internal Medicine/Nephrology, Shifa International Hospital, Islamabad, PAK
| | - Momena Manzoor
- internal Medicine/Nephrology, Shifa International Hospital, Islamabad, PAK
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Tang D, Xu J, Li Y, Zhao P, Kong X, Hu H, Liang S, Tang C, Liu Z. Molecular mechanisms of centipede toxin SsTx-4 inhibition of inwardly rectifying potassium channels. J Biol Chem 2021; 297:101076. [PMID: 34391777 PMCID: PMC8413892 DOI: 10.1016/j.jbc.2021.101076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022] Open
Abstract
Inwardly rectifying potassium channels (Kirs) are important drug targets, with antagonists for the Kir1.1, Kir4.1, and pancreatic Kir6.2/SUR1 channels being potential drug candidates for treating hypertension, depression, and diabetes, respectively. However, few peptide toxins acting on Kirs are identified and their interacting mechanisms remain largely elusive yet. Herein, we showed that the centipede toxin SsTx-4 potently inhibited the Kir1.1, Kir4.1, and Kir6.2/SUR1 channels with nanomolar to submicromolar affinities and intensively studied the molecular bases for toxin–channel interactions using patch-clamp analysis and site-directed mutations. Other Kirs including Kir2.1 to 2.4, Kir4.2, and Kir7.1 were resistant to SsTx-4 treatment. Moreover, SsTx-4 inhibited the inward and outward currents of Kirs with different potencies, possibly caused by a K+ “knock-off” effect, suggesting the toxin functions as an out pore blocker physically occluding the K+-conducting pathway. This conclusion was further supported by a mutation analysis showing that M137 located in the outer vestibule of the Kir6.2/ΔC26 channel was the key residue mediating interaction with SsTx-4. On the other hand, the molecular determinants within SsTx-4 for binding these Kir channels only partially overlapped, with K13 and F44 being the common key residues. Most importantly, K11A, P15A, and Y16A mutant toxins showed improved affinity and/or selectivity toward Kir6.2, while R12A mutant toxin had increased affinity for Kir4.1. To our knowledge, SsTx-4 is the first characterized peptide toxin with Kir4.1 inhibitory activity. This study provides useful insights for engineering a Kir6.2/SUR1 channel–specific antagonist based on the SsTx-4 template molecule and may be useful in developing new antidiabetic drugs.
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Affiliation(s)
- Dongfang Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China; College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Jiahui Xu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Yinping Li
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Piao Zhao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiangjin Kong
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Haoliang Hu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Cheng Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
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