Since the initial report of the association of a truncation mutation of OPHN1 with XLID (Billuart et al., 1998a,b), additional studies have associated nonsynonymous rare missense variants in OPHN1 with ASD (e.g., H705R) and schizophrenia (e.g., M461V) (Piton et al., 2011). This evidence concerns the gene OPHN1 and cask-related x-linked intellectual disability.