Mental Retardation, Autosomal Dominant 4

Clinical Features

Bhalla et al. (2008) reported a 56-year-old white woman (CMS3377) with severe mental retardation (IQ of 16). Facial dysmorphic features included alternating exotropia, flat midface, some downslanting of the lower eyelids, thin nasal bridge, rounded nasal tip, nasal septum below the alae nasi, and small chin. She also had short fifth fingers and fingernails, broad and short feet with short toes, and syndactyly of several toes.

Cytogenetics

In a woman (CMS3377) with severe mental retardation and dysmorphic facial features, Bhalla et al. (2008) identified an apparently balanced translocation t(11;16)(q24.2;q24) with breakpoints in the first intron of the KIRREL3 gene and the second intron of the CDH15 gene (114019). Expression of CDH15 and KIRREL3 was 38 to 45% lower in patient cells compared to controls. No mutations were identified in either gene in this patient.

Molecular Genetics

Associations Pending Confirmation

In 5 of 647 unrelated patients with mental retardation, Bhalla et al. (2008) identified 3 different heterozygous missense mutations in the KIRREL3 gene (607761.0001-607761.0003). Detailed clinical features were not given.