Purpose:We sought to determine the usefulness of fragile X mental retardation 1 (FMR1) carrier testing among young infertile women with or without signs of ovarian insufficiency as compared with fertile women.Methods:Three cohorts of women were recruited to determine the cytosine-guanine-guanine (CGG) repeats trinucleotide repeat length in the 5'-untranslated region of the FMR1 gene in lymphocyte DNA. A total of 199 fertile women, who were reported to have conceived within 3 months, were recruited together with 372 infertile women with ongoing menstrual cycles and 48 infertile women with primary ovarian insufficiency. The various ranges of FMR1 CGG repeat lengths among infertile women were compared with those of fertile controls. In infertile women with ongoing menstrual cycles, the serum concentrations of follicle-stimulating hormone, anti-Muellerian hormone, and inhibin B were measured during the early follicular phase.Results:None of the three categories of FMR1 CGG repeat length expansions (premutation, intermediate range, and high normal range) were more prevalent among infertile women than among fertile women. The CGG repeat length was not correlated with any of the ovarian reserve parameters.Conclusion:In comparison with a generalized preconception screening strategy, infertility as a criterion, even together with reduced ovarian reserve, is not suitable for identifying a higher proportion of women with expanded FMR1 CGG repeat length.Genet Med advance online publication 10 October 2013Genetics in Medicine (2013); doi:10.1038/gim.2013.146.