Mental Retardation, X-Linked 42

Clinical Features

Golla et al. (2002) reported a family in which 4 males had mild to moderate nonspecific X-linked mental retardation, with no intellectual impairment in their obligate carrier mothers.

Mapping

By linkage analysis in a family in which 4 affected males had nonsyndromic mental retardation, Golla et al. (2002) obtained the same multipoint lod score of 2.08 for 2 intervals on the X chromosome: one in the pericentromeric region and the other at Xq26. Since the responsible gene was not characterized, haplotyping was the only means available for carrier and prenatal testing for this form of MRX, which they designated MRX42. Carrier risk estimation using pedigree and haplotype data for 5 females at risk was presented, and the difficulties of prenatal diagnosis given linkage to 2 different regions was discussed.