In order to study the functional role of KMT2C in neurons and thus infer how KMT2C mutations may be implicated in the intellectual disability syndrome phenotype, studies were conducted in Drosophila trr, which shares a one-to-two evolutionary relationship with human orthologs KMT2C and KMT2D. Because homozygous mutations in trr are lethal, a Gal4/UAS system and inducible RNA interference (RNAi) system were employed to ascertain the role of trr in the adult fly nervous system. Here, KMT2C is linked to syndromic intellectual disability.