PCDH19 and Dravet syndrome: In most cases, DS is related to a genetic disorder, and in particular, the syndrome is linked by pathogenic variants in the sodium channel gene SCN1A. Other genes associated with DS include SCN2A, SCN8A, SCN9A, SCN1B, PCDH19, GABRA1, GABRG2, STXBP1, HCN1, CHD2, and KCNA2 (4, 55, 59–62).