Familial triome analysis identified 5 patients with de novo variants in candidate genes not previously reported in association with LKS or other types of epilepsy (see Table 4): TRPC1 (c.961‐2A>C), ERRFI1 (c.566_567delCT, [p.S189*]), CTXN3 (c.164C>T, [p.P55L]), IRX6 (c.1334C>A, [p.A445E]), and IQCA1 (c.357 + 1G>T). This evidence concerns the gene CTXN3 and developmental and/or epileptic encephalopathy with spike-wave activation in sleep.