title: Multipoint genetic mapping of the Xq26-q28 region in families with fragile X mental retardation and in normal families reveals tight linkage of markers in q26-q27.
abstract: The q26-q28 region of the human X chromosome contains several important disease loci, including the locus for the fragile X mental retardation syndrome. We have characterized new polymorphic DNA markers useful for the genetic mapping of this region. They include a new Bell restriction fragment length polymorphism (RFLP) detected by the probe St14-1 (DXS52) and which may therefore be of diagnostic use in hemophilia A families. A linkage analysis was performed in fragile X families and in large normal families from the Centre d'Etude du Polymorphisme Humain (CEPH) by using seven polymorphic loci located in Xq26-q28. This multipoint linkage study allowed us to establish the order centromere-DXS100-DXS86-DXS144-DXS51-F9-FRAX+ ++-(DXS52-DXS15). Together with other studies, our results define a cluster of nine loci that are located in Xq26-q27 and map within a 10 to 15 centimorgan region. This contrasts with the paucity of markers (other than the fragile X locus) between the F9 gene in q27 and the G6PD cluster in q28, which are separated by about 30% recombination.
mesh_terms: D002874:Chromosome Mapping; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics; D008126:Lod Score; D008297:Male; D010375:Pedigree; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D012984:Software; D014960:X Chromosome
chemical_list: D005819:Genetic Markers