SCN5A variants in Japanese patients with left ventricular noncompaction and arrhythmia

Left ventricular noncompaction (LVNC) is a genetically heterogenous disorder. Mutations in the human cardiac sodium channel alpha-subunit gene (SCN5A) are involved in the pathophysiology of cardiac arrhythmias and cardiomyopathies. This study was performed to compare the frequency of SCN5A variants in LVNC patients with or without arrhythmias, and to investigate the relationship between variants and disease severity. DNA was isolated from the peripheral blood of 62 Japanese probands with LVNC, comprising 17 familial cases and 45 sporadic cases. Blood samples were screened for variants in SCN5A using single-strand conformational polymorphism analysis (SSCP) and DNA sequencing. Seven variants, rs6599230:G > A, c.453C > T, c.1141-3C > A, rs1805124:A > G (p.H558R), rs1805125:C > T (p.P1090L), c.3996C > T, and rs1805126:T > C were identified in 7 familial and 12 sporadic cases. The frequency of SCN5A variants was significantly higher in the patients with arrhythmias than those without (50% vs 7%: P = 0.0003), suggesting these variants represent a risk factor for arrhythmia and supporting the hypothesis that genes encoding ion channels are involved in LVNC pathophysiology. The LVNC patients with heart failure also had high occurence of SCN5A variants, suggesting the presence of SCN5A variants and/or arrhythmias increase the severity of LVNC.