Intellectual Developmental Disorder, Autosomal Recessive 28, is also known as mental retardation, autosomal recessive 28. An important gene associated with Intellectual Developmental Disorder, Autosomal Recessive 28 is MRT28 (Mental Retardation, Non-Syndromic, Autosomal Recessive, 28). Related phenotypes are delayed speech and language development and microcephaly