Intellectual Developmental Disorder, X-Linked 77, also known as mental retardation, x-linked 77, is related to non-syndromic x-linked intellectual disability 77 and alpha-thalassemia/impaired intellectual development syndrome, x-linked. An important gene associated with Intellectual Developmental Disorder, X-Linked 77 is MRX77 (Mental Retardation, X-Linked 77). Related phenotypes are intellectual disability and hyperactivity