Mental Retardation, X-Linked, Syndromic, Chudley-Schwartz Type

Clinical Features

Chudley et al. (1999) reported a family in which 3 males spanning 2 generations had a syndromic form of moderate mental retardation with seizures and dysmorphic facial features. Common dysmorphic features included prominent glabella, prognathism, synophrys, and hirsutism; hypertelorism and large ears were each noted in 2 patients. The 2 older patients, who were in their forties, showed slowly progressive unsteady gait and progressive weakness, and 1 of them was found to have cerebellar atrophy and electrophysiologic evidence of a peripheral neuropathy. All had low serum immunoglobulins and 2 had specific absence of plasma and secretory IgA, although only 1 patient had recurrent infections.

Mapping

Using microsatellite markers on the X chromosome to evaluate a family with X-linked syndromic mental retardation, Chudley et al. (1999) found linkage to a region on chromosome Xq21.33-q23 between DXS1170 and DXS8067 (maximum 2-point lod score of 2.23 at DXS1120). Haplotype analysis delineated a region either 16 or 20 Mb in size.