SCN1A Variants in Patients with Dravet Syndrome

ABSTRACT

PURPOSE: The aim of this study is to examine the SCN1A variants in Korean patients with Dravet syndrome. METHODS: We conducted a retrospective study of clinically confirmed thirty-nine patients with Dravet syndrome who visit our hospital from January 2007 to May 2015. We analyzed the SCN1A variants by direct sequencing. We analyzed and classified SCN1A variants according to ACMG/AMP (American College of Medical Genetics and Genomics and the Association for Molecular Pathology) guideline. RESULTS: A total thirty-nine patients (female 22, male 17) were included. Among them, twenty patients (51.2%) with Dravet syndrome had pathogenic or likely pathogenic SCN1A mutations including fifteen truncating mutations (12 nonsense and 3 splice region mutations), 5 missense mutations. The remained variants in nineteen patients with Dravet syndrome classified into ten variants of unknown significances, and 9 benign variants. In our study, truncation mutations are located whole span of SCN1A protein, while half of missense mutations are located at higher density on pore loop (S5-S6) regions. CONCLUSION: Unlike previous known study, lower positive rate of SCN1A mutation of Dravet syndrome was revealed in our study. The importance of parental test (trio test) and other additional tests have been emphasized.