OPHN1 and cask-related x-linked intellectual disability: The Oligophrenin-1 gene (Ophn1) is involved in a syndromic form of X-linked ID (XLID) with cerebellar hypoplasia, and missense mutations in Ophn1 are also associated with schizophrenia and autism spectrum disorders [7,8,9], making this gene a strong candidate (category 2) according to the Simons Foundation Autism Research Initiative (SFARI) score [10].