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Tan BY, Yong RYY, Barajas-Martinez H, Dumaine R, Chew YX, Wasan PS, Ching CK, Ho KL, Gan LSH, Morin N, Chong APL, Yap SH, Neo JL, Yap EPH, Moochhala S, Chong DTT, Chow W, Seow SC, Hu D, Uttamchandani M, Teo WS. A Brugada syndrome proband with compound heterozygote SCN5A mutations identified from a Chinese family in Singapore. Europace 2015; 18:897-904. [PMID: 25829473 DOI: 10.1093/europace/euv058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/20/2015] [Indexed: 01/08/2023] Open
Abstract
AIMS Brugada syndrome (BrS) is a rare heritable ventricular arrhythmia. Genetic defects in SCN5A, a gene that encodes the α-subunit of the sodium ion channel Nav1.5, are present in 15-30% of BrS cases. SCN5A remains by far, the highest yielding gene for BrS. We studied a young male who presented with syncope at age 11. This proband was screened for possible disease causing SCN5A mutations. The inheritance pattern was also examined amongst his first-degree family members. METHODS AND RESULTS The proband had a baseline electrocardiogram that showed Type 2 BrS changes, which escalated to a characteristic Type I BrS pattern during a treadmill test before polymorphic ventricular tachycardia onset at a cycle length of 250 ms. Mutational analysis across all 29 exons in SCN5A of the proband and first-degree relatives of the family revealed that the proband inherited a compound heterozygote mutation in SCN5A, specifically p.A226V and p.R1629X from each parent. To further elucidate the functional changes arising through these mutations, patch-clamp electrophysiology was performed in TSA201 cells expressing the mutated SCN5A channels. The p.A226V mutation significantly reduced peak sodium current (INa) to 24% of wild type (WT) whereas the p.R1629X mutation abolished the current. To mimic the functional state in our proband, functional expression of the compound variants A226V + R1629X resulted in overall peak INa of only 13% of WT (P < 0.01). CONCLUSION Our study is the first to report a SCN5A compound heterozygote in a Singaporean Chinese family. Only the proband carrying both mutations displayed the BrS phenotype, thus providing insights into the expression and penetrance of BrS in an Asian setting.
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Affiliation(s)
- Boon Yew Tan
- National Heart Centre Singapore, 5 Hospital Drive, Singapore 169609, Singapore
| | - Rita Yu Yin Yong
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore Saw Swee Hock School of Public Health, Tahir Foundation Building, National University of Singapore, 12 Science Drive 2, Singapore 117549, Singapore
| | - Hector Barajas-Martinez
- Molecular Genetics Department, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY 13501, USA
| | - Robert Dumaine
- Department of Physiology and Biophysics, Université de Sherbrooke, 2500, boul. de l'Université, Sherbrooke, QC, Canada J1K2R1
| | - Ying Xia Chew
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Pavandip Singh Wasan
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore Saw Swee Hock School of Public Health, Tahir Foundation Building, National University of Singapore, 12 Science Drive 2, Singapore 117549, Singapore
| | - Chi Keong Ching
- National Heart Centre Singapore, 5 Hospital Drive, Singapore 169609, Singapore
| | - Kah Leng Ho
- National Heart Centre Singapore, 5 Hospital Drive, Singapore 169609, Singapore
| | - Linda Seo Hwee Gan
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Nathalie Morin
- Department of Physiology and Biophysics, Université de Sherbrooke, 2500, boul. de l'Université, Sherbrooke, QC, Canada J1K2R1
| | - Alicia Poh Leng Chong
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Shiao Hui Yap
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Jia Ling Neo
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | - Eric Peng Huat Yap
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore Lee Kong Chian School of Medicine, Nanyang Technological University, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Shabbir Moochhala
- Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore
| | | | - Weien Chow
- SAF Medical Corps, 701 Transit Road, Singapore 778910, Singapore
| | - Swee Chong Seow
- The Heart Institute, National University Hospital Main Building, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
| | - Dan Hu
- Molecular Genetics Department, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY 13501, USA Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, 99 Zhang Zhi Dong Road, Wuhan 430060, China
| | - Mahesh Uttamchandani
- National Heart Centre Singapore, 5 Hospital Drive, Singapore 169609, Singapore Defence Medical and Environmental Research Institute, DSO National Laboratories, 27 Medical Drive, Singapore 117510, Singapore Department of Biological Sciences and Department of Chemistry, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Wee Siong Teo
- National Heart Centre Singapore, 5 Hospital Drive, Singapore 169609, Singapore
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