HCN1 and Dravet syndrome: In addition to gene mutations of SCN1A that can cause DS, other genes include PCDH19, SCN2A, SCN8A, SCN1B, GABRA1, GABRG2, GABRB3, STXBP1, HCN1, CHD2, and KCNA2 can also cause DS or DS-like phenotypes (4).