Intellectual Developmental Disorder, X-Linked, Syndromic, Claes-Jensen Type, also known as mental retardation, x-linked, syndromic, claes-jensen type, is related to syndromic x-linked intellectual disability claes-jensen type and plasma cell neoplasm. An important gene associated with Intellectual Developmental Disorder, X-Linked, Syndromic, Claes-Jensen Type is KDM5C (Lysine Demethylase 5C). Affiliated tissues include eye and tongue, and related phenotypes are delayed speech and language development and intellectual disability, severe