Mental Retardation, Autosomal Recessive 35

Clinical Features

Al-Owain et al. (2011) described a consanguineous multiplex Saudi family in which 4 sibs had cognitive impairment, hirsutism, dysmorphic facies, and skeletal abnormalities. The sibs had low weight, flat and broad occiput, tall broad forehead, hypertelorism, synophrys, malar hypoplasia, low-set small ears, broad nose with thick alae nasi, everted lower lip, and micrognathia. All had global developmental delay, hypotonia, and short ulna.

Inheritance

Consanguinity and affected sibs in the family reported by Al-Owain et al. (2011) suggested autosomal recessive inheritance of the disorder.

Mapping

By linkage analysis and homozygosity mapping in a consanguineous multiplex Saudi family in which 4 sibs had a mental retardation disorder, Al-Owain et al. (2011) identified a single peak in a 12.2-Mb region on chromosome 17q21.31-q22 between SNPs rs4792947 and rs11079258 with a lod score of 3.504.

Molecular Genetics

Exclusion Studies

In a consanguineous multiplex Saudi family in which 4 sibs had a disorder of cognitive impairment, hirsutism, dysmorphic facies, and skeletal abnormalities linked to chromosome 17q21.31-q22, Al-Owain et al. (2011) sequenced 2 candidate genes, HOXB6 and PPP1R9B, and found no pathogenic alterations.