In contrast with LKS and CSWS (38–42), monogenic mutations including GRIN2A (38, 39, 42), KCNQ2, KCNQ3 or duplications in PRRT2 gene (35, 43–48) have been detected in only a small proportion of children with typical ECTS. This evidence concerns the gene GRIN2A and developmental and/or epileptic encephalopathy with spike-wave activation in sleep.