title: Linkage analysis in Spanish families with nonspecific X-linked mental retardation: Significant linkage at Xq13-q21.
abstract: Mental retardation (MR) is a genetically heterogeneous, clinically variable condition. Many cases of MR are linked to the X chromosome. The aim of this study was to identify candidate loci for nonspecific MR in Spanish samples. We selected seven families with nonspecific MR and a pattern of inheritance compatible with an X-linked disorder and a group of 26 sib pairs of mentally retarded individuals. We performed linkage analysis with a panel of 15 markers evenly distributed along the X chromosome. The study showed linkage to marker DXS8076, located in Xq21.1, by the lod score method (z = 2.11 at straight theta = 0.155) and the nonparametric extended relative pair analysis method (chi(2) = 5.32; P < 0.03). Genetic heterogeneity was found, with an estimated 75% of the families linked at recombination fraction straight theta = 0.10 to the DXS8076 locus (chi(2) = 9.51; P < 0.009). Xq13-q21 is one of the critical regions for X-linked MR previously reported, and our study supports the idea that this region may contain a locus for MR in Spanish patients.
authors.affiliation: Genetics Service, Hospital Clínic, Villaroel 170, 08036 Barcelona, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Badenas
authors.forename: S
authors.initials: S
authors.lastname: Castellví-Bel
authors.forename: V
authors.initials: V
authors.lastname: Volpini
authors.forename: D
authors.initials: D
authors.lastname: Jiménez
authors.forename: A
authors.initials: A
authors.lastname: Sánchez
authors.forename: X
authors.initials: X
authors.lastname: Estivill
authors.forename: M
authors.initials: M
authors.lastname: Milà
mesh_terms: D004247:DNA / Q000235:genetics; D005192:Family Health; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D018895:Microsatellite Repeats; D010375:Pedigree; D012984:Software; D013030:Spain; D014960:X Chromosome / Q000235:genetics*
chemical_list: D004247:DNA