NIPA2 and neurodevelopmental disorder: Some of these genes themselves are of interest in brain development specifically, Nipa2 (non-imprinted in Prader-Willi/Angelman syndrome 2), Sez6 (seizure-related 6 homologs), and Aff4 (AF4/FMR2 family member 4) are involved in neurodevelopmental disorders with complex phenotypes [12, 32, 47, 48, 64].