Here we report on the localization of a presumptive MRX gene to chromosomal region Xq24-q26 in a German family with nonspecific X-linked mental retardation (MRX 75, HUGO Human Gene Nomenclature Committee).
Most considerably, genotype-phenotype correlation studies of affected individuals in XLMR families with MRX gene mutations are necessary to define the criteria of MRX vs MRXS subclassification.
Thorough investigation of an MRX critical region in Xp22.1-21.3 enabled us to identify a new gene expressed in brain that is responsible for a non-specific form of X-linked mental retardation.