Fragile X carrier screening in Korean women of reproductive age

ObjectiveTo estimate the distribution of the FMR1 alleles and the prevalence of the premutaion (PM) and full mutation (FM) of the FMR1 gene in Korean women of reproductive age.MethodsUsing polymerase chain reaction and Southern blot, 5829 women of reproductive age were screened (low-risk group n = 5470 and high-risk group n = 359) and 11 prenatal diagnoses were completed between September 2003 and December 2011.ResultsOf the 5829 women screened, normal FMR1 alleles (11,607) had a bimodal distribution with most alleles having 29 (37.87%) and 30 (31.87%) CGG repeats. Of the 5470 women in the low-risk group, 7 PM were identified, giving a PM carrier frequency of 1:781; none of the women had Fragile X syndrome. We also identified 38 intermediate alleles, with a reported incidence of 1:143. Of the 11 prenatal diagnoses, five were normal, five had a premutation, and one had a full mutation allele.ConclusionsThe carrier frequency is 1/781 (0.13%) in Korean women of reproductive age. This is lower than among Cauc...