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Rossanti R, Horinouchi T, Sakakibara N, Yamamura T, Nagano C, Ishiko S, Aoto Y, Kondo A, Nagai S, Awano H, Nagase H, Matsuo M, Iijima K, Nozu K. Detecting pathogenic deep intronic variants in Gitelman syndrome. Am J Med Genet A 2022; 188:2576-2583. [PMID: 35785516 DOI: 10.1002/ajmg.a.62885] [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: 01/28/2022] [Revised: 05/17/2022] [Accepted: 05/30/2022] [Indexed: 01/24/2023]
Abstract
Gitelman syndrome (GS) is a rare, autosomal recessive, salt-losing tubulopathy caused by loss of function in the SLC12A3 gene (NM_000339.2), which encodes the natrium chloride cotransporter. The detection of homozygous or compound heterozygous SLC12A3 variants is expected in GS, but 18%-40% of patients with clinical GS carry only one mutant allele. Previous reports identified some pathogenic deep intronic variants in SLC12A3. Here, we report the screening of SLC12A3 deep intronic variants in 13 patients with suspected GS carrying one mutated SLC12A3 allele. Variant screening used the HaloPlex Target Enrichment System Kit capturing whole introns and the promotor region of SLC12A3, followed by SureCall variant analysis. Rare intronic variants (<1% frequency) were identified, and pathogenicity evaluated by the minigene system. Deep intronic variant screening detected seven rare SLC12A3 variants from six patients. Only one variant showed pathogenicity in the minigene system (c.602-16G>A, intron 4) through activation of a cryptic acceptor site. No variants were detected in the promotor region. Deep intronic screening identified only one pathogenic variant in patients with suspected GS carrying monoallelic SLC12A3 variants. Our results suggest that deep intronic variants partially explain the cause of monoallelic variants in patients with GS.
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Affiliation(s)
- Rini Rossanti
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan.,Department of Child Health, Nephrology Division, Dr. Hasan Sadikin General Hospital/Faculty of Medicine, Universitas Padjadjaran, Bandung, Indonesia
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shinya Ishiko
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yuya Aoto
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Atsushi Kondo
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Sadayuki Nagai
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroyuki Awano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Nagase
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masafumi Matsuo
- Research Center for Locomotion Biology, Kobe Gakuin University, Kobe, Hyogo, Japan
| | - Kazumoto Iijima
- Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan.,Department of Advanced Pediatric Medicine, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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Qin YZ, Liu YM, Wang Y, You C, Li LN, Zhou XY, Lv WM, Hong SH, Xiao LX. Novel compound heterozygous mutation of SLC12A3 in Gitelman syndrome co-existent with hyperthyroidism: A case report and literature review. World J Clin Cases 2022; 10:7483-7494. [PMID: 36158002 PMCID: PMC9353888 DOI: 10.12998/wjcc.v10.i21.7483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/27/2022] [Accepted: 05/28/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Gitelman syndrome (GS) is a rare inherited autosomal recessive tubulopathy, characterized clinically by hypokalemia, hypomagnesemia, hypocalciuria, and metabolic alkalosis, and is caused by an inactivating mutation in SLC12A3. GS is prone to misdiagnosis when occurring simultaneously with hyperthyroidism. It is important to consider the possibility of other diseases when hyperthyroidism is combined with hypokalemia, which is difficult to correct.
CASE SUMMARY A female patient with hyperthyroidism complicated with limb weakness was diagnosed with thyrotoxic hypokalemic periodic paralysis for 4 mo. However, the patient’s serum potassium level remained low despite sufficient potassium replacement and remission of hyperthyroidism. GS was confirmed by whole exome and Sanger sequencing. Gene sequencing revealed compound heterozygous mutations of c.488C>T (p.Thr163Met), c.2612G>A (p.Arg871His), and c.1171_1178dupGCCACCAT (p.Ile393fs) in SLC12A3. Protein molecular modeling was performed to predict the effects of the identified missense mutations. All three mutations cause changes in protein structure and may result in abnormal protein function. All previously reported cases of GS coexisting with autoimmune thyroid disease are reviewed.
CONCLUSION We have identified a novel compound heterozygous mutation in SLC12A3. The present study provides new genetic evidence for GS.
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Affiliation(s)
- Yong-Zhang Qin
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Yan-Ming Liu
- Department of Endocrinology, The First People’s Hospital of Nankang District, Ganzhou 341400, Jiangxi Province, China
| | - Yang Wang
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Cong You
- Department of Dermatology and Venereology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Long-Nian Li
- Department of Dermatology and Venereology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Xue-Yan Zhou
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Wei-Min Lv
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Shi-Hua Hong
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
| | - Li-Xia Xiao
- Department of Endocrinology, The First Affiliated Hospital of Gannan Medical University, Ganzhou 341000, Jiangxi Province, China
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Reyes JV, Medina PMB. Renal calcium and magnesium handling in Gitelman syndrome. Am J Transl Res 2022; 14:1-19. [PMID: 35173827 PMCID: PMC8829599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Gitelman syndrome (GS) is an autosomal recessive salt-losing tubulopathy caused by biallelic inactivating mutations in the SLC12A3 gene. This gene encodes the thiazide-sensitive sodium-chloride cotransporter (NCC) which is exclusively expressed in the distal convoluted tubules (DCT). GS patients classically present with hypokalemic metabolic alkalosis with hypocalciuria and hypomagnesemia. While hypokalemia and metabolic alkalosis are easily explained by effects of the genotypic defect in GS, the mechanisms by which hypomagnesemia and hypocalciuria develop in GS are poorly understood. In this review, we aim to achieve three major objectives. First, present a concise discussion about current understanding on physiologic calcium and magnesium handling in the DCT. Second, integrate expression data from studies on calciotropic and magnesiotropic proteins relevant to the GS disease state. Lastly, provide insights into the possible mechanisms of calcium-magnesium crosstalk relating to the co-occurrence of hypocalciuria and hypomagnesemia in GS models. Our analyses highlight specific areas of study that are valuable in elucidating possible molecular pathways of hypocalciuria and hypomagnesemia in GS.
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Affiliation(s)
- Jeremiah V Reyes
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
| | - Paul Mark B Medina
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
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Yan MT, Yang SS, Tseng MH, Cheng CJ, Tsai JD, Sung CC, Hsu YJ, Lin SH. Allele-specific RT-PCR for the rapid detection of recurrent SLC12A3 mutations for Gitelman syndrome. NPJ Genom Med 2021; 6:68. [PMID: 34389731 PMCID: PMC8363728 DOI: 10.1038/s41525-021-00230-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/23/2021] [Indexed: 12/20/2022] Open
Abstract
Recurrent mutations in the SLC12A3 gene responsible for autosomal recessive Gitelman syndrome (GS) are frequently reported, but the exact prevalence is unknown. The rapid detection of recurrent SLC12A3 mutations may help in the early diagnosis of GS. This study was aimed to investigate the prevalence of recurrent SLC12A3 mutations in a Taiwan cohort of GS families and develop a simple and rapid method to detect recurrent SLC12A3 mutations. One hundred and thirty independent Taiwan families with genetically confirmed GS were consecutively enrolled to define recurrent SLC12A3 mutations and determine their prevalence. Using TaqMan probe-based real-time polymerase chain reaction, we designed a mutation detection plate with all recurrent mutations. We validated this mutation detection plate and tested its feasibility in newly diagnosed GS patients. A total of 57 mutations in the SLC12A3 gene were identified and 22 including 2 deep intronic mutations were recurrent mutations consisting of 87.1% (242/278, 18 triple) of all allelic mutations. The recurrent mutation-based TaqMan assays were fully validated with excellent sensitivity and specificity in genetically diagnosed GS patients and healthy subjects. In clinical validation, recurrent mutations were recognized in 92.0% of allelic mutations from 12 GS patients within 4 h and all were confirmed by direct sequencing. Recurrent SLC12A3 mutations are very common in Taiwan GS patients and can be rapidly identified by this recurrent mutation-based SLC12A3 mutation plate.
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Affiliation(s)
- Ming-Tso Yan
- Division of Nephrology, Department of Medicine, Cathay General Hospital, School of Medicine, Fu-Jen Catholic University, Taipei, Taiwan.,Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Sung-Sen Yang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan
| | - Min-Hua Tseng
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Pediatric Nephrology, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Chih-Jen Cheng
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan
| | - Jeng-Daw Tsai
- Division of Nephrology, Department of Pediatrics, MacKay Memorial Hospital, Taipei, Taiwan
| | - Chih-Chien Sung
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan
| | - Yu-Juei Hsu
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan
| | - Shih-Hua Lin
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan. .,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan.
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Wan X, Perry J, Zhang H, Jin F, Ryan KA, Van Hout C, Reid J, Overton J, Baras A, Han Z, Streeten E, Li Y, Mitchell BD, Shuldiner AR, Fu M. Heterozygosity for a Pathogenic Variant in SLC12A3 That Causes Autosomal Recessive Gitelman Syndrome Is Associated with Lower Serum Potassium. J Am Soc Nephrol 2021; 32:756-765. [PMID: 33542107 PMCID: PMC7920171 DOI: 10.1681/asn.2020071030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 12/03/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Potassium levels regulate multiple physiologic processes. The heritability of serum potassium level is moderate, with published estimates varying from 17% to 60%, suggesting genetic influences. However, the genetic determinants of potassium levels are not generally known. METHODS A whole-exome sequencing association study of serum potassium levels in 5812 subjects of the Old Order Amish was performed. A dietary salt intervention in 533 Amish subjects estimated interaction between p.R642G and sodium intake. RESULTS A cluster of variants, spanning approximately 537 kb on chromosome 16q13, was significantly associated with serum potassium levels. Among the associated variants, a known pathogenic variant of autosomal recessive Gitelman syndrome (p.R642G SLC12A3) was most likely causal; there were no homozygotes in our sample. Heterozygosity for p.R642G was also associated with lower chloride levels, but not with sodium levels. Notably, p.R642G showed a novel association with lower serum BUN levels. Heterozygotes for p.R642G had a two-fold higher rate of self-reported bone fractures and had higher resting heart rates on a low-salt diet compared with noncarriers. CONCLUSIONS This study provides evidence that heterozygosity for a pathogenic variant in SLC12A3 causing Gitelman syndrome, a canonically recessive disorder, contributes to serum potassium concentration. The findings provide insights into SLC12A3 biology and the effects of heterozygosity on electrolyte homeostasis and related subclinical phenotypes that may have implications for personalized medicine and nutrition.
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Affiliation(s)
- Xuesi Wan
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland,Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - James Perry
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Haichen Zhang
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Feng Jin
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kathleen A. Ryan
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | | | | | | | - Aris Baras
- Regeneron Genetics Center, Tarrytown, New York
| | - Zhe Han
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Elizabeth Streeten
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Yanbing Li
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Braxton D. Mitchell
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | | | - Mao Fu
- Program in Personalized and Genomic Medicine, Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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