AP1S2 and X-linked intellectual disability - Dandy-Walker malformation - basal ganglia disease - Seizures: Pettigrew syndrome (PGS) (also called fried‐type syndromic mental retardation) is due to the AP1S2 gene mutation and belongs to the syndrome form of XLD (Cacciagli et al., 2014; Pettigrew, Jackson, & Ledbetter, 1991).