HCN1 and Dravet syndrome: Genes that cause DS can be grouped based on how they work: specifically, three sodium channel-related genes (SCN2A, SCN8A, and SCN1B), one potassium channel-related gene (KCNA2), three gamma-aminobutyric acid receptors (GABAR) genes (GABRA2, GABRB3, and GABRG2), a cyclic nucleotide gated cation channel gene (HCN1), and other functional genes including CHD2, CPLX1, and STXBP1. Approximately 80% of patients with DS have a pathogenic variant of the SCN1A gene, from which the majority of SCN1A variants are de novo, but 10% of people inherit the SCNA1 mutation from one or both parents [6].