Delineation of the clinical phenotype associated with OPHN1 mutations based on the clinical and neuropsychological evaluation of three families.

Recent reports have demonstrated that mutations in the OPHN1 gene were responsible for a syndromic rather than non-specific mental retardation. Abnormalities of the posterior fossa with cerebellar hypoplasia have been demonstrated in all male patients reported to date. We report here a new family with X-linked mental retardation due to mutation in OPHN1 and present unpublished data about two families previously reported, concerning the facial and psychological phenotype of affected males and carrier females. Our study confirms that cerebellar hypoplasia is a hallmark of this syndrome. In addition, affected males display facial similarities that can help the diagnosis. Most carrier females have mild mental retardation and subtle facial changes.