title: Dissociation between mental retardation and fragile site expression in a family with fragile X-linked mental retardation.
abstract: We report an extended family in which two brothers with a fragile X chromosome are mentally retarded while a third brother with the fragile site is both phenotypically and mentally normal. The study of six probes detecting restriction fragment length polymorphisms on either sides of the fragile site Xq27 confirmed that the fragile X regions inherited by these three brothers were identical from DXS102 to the telomere. These data highlight the heterogeneity of the fragile X syndrome, which is discussed in the framework of the different hypotheses previously proposed.
authors.affiliation: Centre de Génétique Médicale et INSERM U. 242, Hôpital d'Enfants de la Timone, Marseille, France.
authors.forename: M A
authors.initials: MA
authors.lastname: Voelckel
authors.forename: M G
authors.initials: MG
authors.lastname: Mattei
authors.forename: C
authors.initials: C
authors.lastname: N'Guyen
authors.forename: N
authors.initials: N
authors.lastname: Philip
authors.forename: F
authors.initials: F
authors.lastname: Birg
authors.forename: J F
authors.initials: JF
authors.lastname: Mattei
mesh_terms: D002648:Child; D015342:DNA Probes; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D008040:Genetic Linkage; D014644:Genetic Variation; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D012729:Sex Chromosome Aberrations / Q000235:genetics*
chemical_list: D015342:DNA Probes