Abstract
The number of couples at risk for having a child with fragile X syndrome is twice that of cystic fibrosis, based on a fragile X premutation carrier rate of 1 in 259 women. Its prevalence and the availability of highly accurate laboratory testing have raised the possibility of population screening for fragile X mutations. We offered fragile X carrier testing to over 300 pregnant women seen for prenatal genetic counseling, a majority of whom had been referred for advanced maternal age and abnormal triple screen results. Women were informed about the testing through an explanatory pamphlet and face-to-face discussion with a genetic counselor. Testing was offered free of charge except in cases where such testing would have been indicated based on a personal or family history of mental retardation, in which case insurance was billed. A majority of women agreed to testing. The prevalence of women with pre- and full mutations in our cohort was consistent with previous estimates, although a larger than anticipated number of women had results in the premutation “gray zone” between 40 and 50 CGG repeats. Acceptance rates were significantly lower among women referred for discussion of abnormal triple screen results. This subset of women was much less likely than the rest of the cohort to accept fragile X carrier testing, even when they opted for invasive prenatal diagnostic procedures for chromosome abnormalities.
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Finucane, B., Speare, V., Allitto, B. et al. Fragile X mutation screening among unselected pregnant women seen for genetic counseling: Findings of a pilot study. Genet Med 1, 54 (1999). https://doi.org/10.1097/00125817-199901000-00051
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DOI: https://doi.org/10.1097/00125817-199901000-00051