Relevance of triple CGG repeats in the FMR1 gene to ovarian reserve

Most individuals demonstrate 29–30 CGG triple repeats on the FMR1 gene. This may functionally represent a normal range in regard to ovarian reserve. Higher counts reflect risk towards premature ovarian senescence, but lower counts have not been investigated before and, therefore, were the principal subject of this investigation. Amongst 316 consecutive infertility patients, 94 demonstrated <28 repeats (group A), 163 28–33 repeats (group B, considered normal repeat numbers) and 59 ≥34 repeats (group C). The three groups did not differ in age, FSH or anti-Müllerian hormone (AMH) concentrations. Neither FSH nor AMH correlated in linear regression with <28 CGG repeats. In logistic regression, AMH of ≤0.8 ng/ml (indicative of diminished ovarian reserve at all ages) was, however, significantly associated with number of repeats (P < 0.001). Every decrease by five CGG repeats in group A increased the likelihood of diminished ovarian reserve by 40%, while every increase by five CGG repeats in group C increased risk by 50% (both P <0.002). AMH of ≤0.8 ng/ml statistically correlated overall with decreasing triple CGG repeats throughout all ranges (P < 0.001). Approximately 29–30 CGG repeats appear reflective of normal ovarian reserve, with higher and lower counts denoting similar risks towards premature ovarian senescence.