Intellectual Developmental Disorder, X-Linked 72, also known as xlid72, is related to non-syndromic x-linked intellectual disability 72 and fragile x syndrome. An important gene associated with Intellectual Developmental Disorder, X-Linked 72 is RAB39B (RAB39B, Member RAS Oncogene Family). Affiliated tissues include brain, and related phenotypes are intellectual disability and macrocephaly