NO FOUNDER EFFECT DETECTED IN JEWISH ASHKENAZI PATIENTS WITH FRAGILE-X-SYNDROME

Several studies on small homogenous populations suggested that fragile -X syndrome originated from a limited number of founder chromosomes. T he Israeli Jewish population could serve as an adequate model for trac ing a founder effect due to the unique ethnic makeup and traditional l ifestyle. 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, u sing microsatellite markers within and flanking the FMR-1 gene: FRAXAC 1, 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 th at no common ancestral X chromosome is associated with the fragile-X s yndrome in the Israeli Jewish Ashkenazi patient population studied. Th ese findings are in contrast to other reports on founder effect associ ated with fragile-X syndrome in distinct European as well as Jewish Tu nisian populations. On this basis, a more complex mechanism for the de velopment of fragile-X syndrome in the Jewish Ashkenazi population sho uld be considered.