Monarch Disease Ontology identifier MONDO_0010337 (X-linked intellectual disability-cerebellar hypoplasia syndrome) can be described as follows. X-linked intellectual deficit-cerebellar hypoplasia, also known as OPHN1 syndrome, is a rare syndromic form of cerebellar dysgenesis characterized by moderate to severe intellectual deficit and cerebellar abnormalities. Also known as: OPHN1 syndrome, Oligophrenin-1 syndrome, intellectual developmental disorder, X-linked syndromic, Billuart type, X-linked recessive.