title: XLMR genes: update 1996.
abstract: A current list of all known forms of X-linked mental retardation (XLMR) and a slightly revised classification are presented. The number of known disorders has not increased because 6 disorders have been combined based on new molecular data or on clinical grounds and only 6 newly described XLMR disorders have been reported. Of the current 105 XLMR disorders, 34 have been mapped, and 18 disorders and 1 nonspecific XLMR (FRAXE) have been cloned. The number of families with nonspecific XLMR with a LOD score of > or = 2.0 has more than doubled, with 42 (including FRAXE) now being known. a summary of the localization of presumed nonspecific mental retardation (MR) genes from well-studied X-chromosomal translocations and deletions is also included. Only 10-12 nonoverlapping loci are required to explain all localizations of nonspecific MR from both approaches. These new trends mark the beginning of a significantly improved understanding of the role of genes on the X chromosome in producing MR. Continued close collaboration between clinical and molecular investigators will be required to complete the process.
authors.affiliation: Department of Medical Genetics, University Hospital of Tromsø, Norway.
authors.forename: H A
authors.initials: HA
authors.lastname: Lubs
authors.forename: P
authors.initials: P
authors.lastname: Chiurazzi
authors.forename: J F
authors.initials: JF
authors.lastname: Arena
authors.forename: C
authors.initials: C
authors.lastname: Schwartz
authors.forename: L
authors.initials: L
authors.lastname: Tranebjaerg
authors.forename: G
authors.initials: G
authors.lastname: Neri
mesh_terms: D002874:Chromosome Mapping; D003001:Cloning, Molecular; D030342:Genetic Diseases, Inborn / Q000235:genetics; D008040:Genetic Linkage; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D014960:X Chromosome