Eight of those (SCN1A, IQSEC2, STXBP1, CACNA1E, ARID1B, DDX3X, WHSC1, PHF21A) have been known to be responsible for NDDs associated with IDs or epilepsies.9, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29. Here, NSD2 is linked to epilepsy.