Original article pilot screening for fragile X carrier in pregnant women of southern Taiwan.

BACKGROUND: Carrier detection before or at early pregnancy through a wide screening program may be a practical approach to prevent the fragile X syndrome. However, prior to implementation of such a program, the carrier prevalence in a population and availability of effective screening tests should be evaluated. METHODS: One thousand and two pregnant women were randomly selected from our obstetric clinic and screened for FMRI mutation. Each woman was examined individually using a simple non-radioactive PCR, as well as in pool with two other women using high-resolution Southern blot hybridization. RESULTS: One third of women could be excluded from carrier status by PCR alone, while the rest had to be screened using Southern-blot hybridization in pool with two other women. This screening strategy was reliable and efficient, and suitable for large-scale screening. Among the 1002 women, no carrier of either premutation or full mutation was found. Allele with intermediate CGG-repeat between 40 and 52 was found in only 22 women (2.2%). CONCLUSIONS: Estimation of female fragile X carrier rate in Taiwan could not be made in the present study, due to insufficient sample size. However, the results indicated clearly that the rate in Taiwan was significantly lower than that of Israel (0/1002 vs. 1/113, p = 0.003), and also lower than those from other western counties (1/186-259, p = 0.020-0.049). We doubt that the cost-efficiency of such a wide screening program in Taiwan is acceptable. However, the effective screening strategy proposed in this study would be very helpful for women with family history of mental deficiency of undetermined etiology.