title: No founder effect detected in Jewish Ashkenazi patients with fragile-X syndrome.
abstract: Several studies on small homogenous populations suggested that fragile-X syndrome originated from a limited number of founder chromosomes. The Israeli Jewish population could serve as an adequate model for tracing a founder effect due to the unique ethnic makeup and traditional lifestyle. Furthermore, a common haplotype for Jewish Tunisian fragile X patients was recently reported. To test for a similar occurrence in the Jewish Ashkenazi population, we performed haplotype analysis of 23 fragile-X patients and 28 normal chromosomes, all Jewish Ashkenazi, using microsatellite markers within and flanking the FMR-1 gene: FRAXAC1, FRAXAC2, and DXS548. The combined triple-marker analysis identified a wide range of diverse haplotypes in patients and controls, with no distinct haplotype prevalent in the patient group. Our data suggest that no common ancestral X chromosome is associated with the fragile-X syndrome in the Israeli Jewish Ashkenazi patient population studied. These findings are in contrast to other reports on founder effect associated with fragile-X syndrome in distinct European as well as Jewish Tunisian populations. On this basis, a more complex mechanism for the development of fragile-X syndrome in the Jewish Ashkenazi population should be considered.
authors.affiliation: Susanne Levy Oncogenetics Laboratory Genetics Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Pesso
authors.forename: G
authors.initials: G
authors.lastname: Barkai
authors.forename: Y
authors.initials: Y
authors.lastname: Ravia
authors.forename: E
authors.initials: E
authors.lastname: Gak
authors.forename: M
authors.initials: M
authors.lastname: Frydman
authors.forename: B
authors.initials: B
authors.lastname: Goldman
authors.forename: E
authors.initials: E
authors.lastname: Friedman
mesh_terms: D005060:Europe / Q000208:ethnology; D018703:Founder Effect; D005600:Fragile X Syndrome / Q000453:epidemiology / Q000235:genetics*; D005819:Genetic Markers; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D007557:Israel / Q000453:epidemiology; D007585:Jews / Q000235:genetics*; D008297:Male; D016133:Polymerase Chain Reaction
chemical_list: D005819:Genetic Markers