Background: Mutations of human cardiac sodium channel alpha subunit gene (SCN5A) have been implicated in risk of various cardiac arrhythmias. The present study aimed to investigate whether SCN5A polymorphism was related to the occurrence of idiopathic ventricular arrhythmia (IVA) in Chinese Han patients.
Methods and results: Genotyping for polymorphic variance of SCN5A was performed by polymerase chain reaction and automated gene scan sequencing analysis in 31 unrelated Chinese patients with IVA (IVA group) and 103 healthy controls (control group). The allele frequencies of c.87G>A (p.Ala29Ala) and c.1673A>G (p.His558Arg) were higher in men than in women for control group (p=0.023 and p=0.027, respectively). For women, patients with IVA had higher allele frequency of c.87G>A than controls (0.455 vs 0.198, p=0.013, odds ratio (OR) 3.382), whereas for men, minor allele c.1673A>G was significantly less prevalent in IVA patients compared with controls (0.025 vs 0.175, p=0.017, OR 0.121). Significant difference existed in occurrence of ventricular arrhythmia between female patients with 87GA/AA and those with 87GG genotypes (0.348 vs 0.097, p=0.039, OR 4.978) and between male patients with 1673AA and those with 1673AG/GG genotypes (0.311 vs 0.053, p=0.031, OR 8.143). The frequency of haplotype GG (87G-1673G) was significantly lower in IVA patients than in controls (0.016 vs 0.128, p=0.009, OR 0.109).
Conclusions: The present study indicates that Chinese Han people have significant difference in distribution of 2 single nucleotide polymorphisms (c.87G>A and c.1673A>G) between healthy male and females. The 87A allele might be associated with an increased risk of IVA in females, whereas 1673G allele might have been positively selected because of its protective effects against ventricular arrhythmia in males.