Retinopathy, Pigmentary, And Mental Retardation

Clinical Features

Mirhosseini et al. (1972) described 2 brothers with pigmentary retinal degeneration, cataract, microcephaly, severe mental retardation, hyperextensible joints, scoliosis, and arachnodactyly. One had hypogonadism. The parents were apparently not related. Mendez et al. (1985) reported the cases of 2 sisters with first-cousin parents.

Horn et al. (2000) reported 2 brothers and a cousin from a multiply consanguineous kindred of Lebanese descent with a syndrome of microcephaly, progressive postnatal growth deficiency, mental retardation, hypotonia, chorioretinal dystrophy, and myopia. The severity of the condition varied among the affected family members.

Mapping

By homozygosity mapping, Horn et al. (2000) localized the gene responsible for the disorder in their family to a 26.8-cM region on chromosome 8q21.3-q22.1. This region overlaps the refined gene region for Cohen syndrome (COH1; 216550). Horn et al. (2000) hypothesized that the syndrome in their family, Cohen syndrome, and Mirhosseini-Holmes-Walton syndrome may be allelic.