Association between SCN5A and sudden unexplained nocturnal death syndrome in Thai decedents: a case–control study

Sudden unexplained nocturnal death syndrome (SUNDS) is a genetic disorder that can cause sudden death in young and healthy adults during sleep at night. Cardiac arrhythmia has been proposed as the factor responsible for such deaths. This study was thus aimed to investigate the association between SCN5A , the gene that has been extensively studied and thought to be associated with cardiac conduction system abnormality causing sudden cardiac death, and SUNDS in Thai decedents. Genomic DNA was extracted using blood samples from 12 unrelated SUNDS subjects and 151 unrelated non-SUNDS control decedents. Subjects were divided into three subgroups as follows: subjects who resided in regions other than Northeastern Thailand ( n = 99), age-matched subjects who resided in Northeastern Thailand ( n = 28), and subjects older than 40 years who resided in Northeastern Thailand ( n = 24). Genomic DNA from SUNDS cases was screened for genetic variations for the entire 28 coding exons of SCN5A . The identified variants were also genotyped in control subjects using high-resolution melting analysis and sequencing. Twelve variants of SCN5A were identified, including six polymorphisms and another six variants previously reported to be related with cardiac conduction defects. Two identified variants (rs1805126 and rs7429945) deserved further study because of their strong odd ratios.