XLMR genes: Update 1992

Abstract
Up to now, we have identified 77 X‐linked conditions in which mental retardation is the primary or a major component manifestation. These conditions were subdivided into 2 categories, designated respectively “X‐linked mental retardation syndromes” and “Non‐specific X‐linked mental retardation”. Forty genes have been regionally mapped onto the X chromosome. However, in several instances the data were derived from a single family and most lod scores were less than 3.0.