The ovarian response in fragile X patients and premutation carriers undergoing IVF-PGD: reappraisal

Abstract

Study question: What is the association between the ovarian response and the number of CGG repeats among full mutation and premutation carriers of fragile X (FMR1), undergoing controlled ovarian hyperstimulation (COH) for PGD?

Summary answer: Ovarian response was normal in full mutation patients but decreased in premutation carriers, although the number of repeats was not statistically significantly associated with the number of oocytes retrieved.

What is known already: There is inconsistent data in the literature regarding ovarian response in FMR1 carriers. Studies exploring the ovarian response of full mutation patients are lacking.

Study design, size, duration: Retrospective study, a university affiliated tertiary hospital, IVF unit, PGD referral center.

Participants/materials, setting, methods: We examined the medical records of all women undergoing fresh IVF-PGD cycles due to fragile X. Data recorded included demography, duration of stimulation, amount of gonadotropins administered, number of dominant follicles, maximal E2 levels and number of oocytes retrieved. Data were analyzed using univariate and multivariate mixed models. P-values <0.05 were considered significant. Data were collected from the medical records of 21 patients with a full mutation on the FMR1 gene and 51 premutation carriers. Overall 309 fresh cycles were analyzed.

Main results and the role of chance: Premutation carriers displayed reduced ovarian response, as demonstrated by fewer oocytes retrieved. In contrast, full mutation patients had a normal response. Comparison of premutation carriers and full mutation patients showed: mean oocytes retrieved per cycle (8.4 ± 1.1 versus 14.1 ± 1.7, P = 0.005), lower levels of estradiol (E2; 1756 ± 177, versus 2928 ± 263, P = 0.0004), respectively. There was no significant difference between premutation carriers and full mutation patients in regard to fertilization rate, cleavage rate or biopsy rate. No correlation was found between the number of repeats in the premutation carriers and the number of oocytes retrieved or E2 levels. Age and the type of protocol were the only factors found to be in correlation with the number of the oocyte retrieved (P = 0.037, and P = 0.003, respectively) among the premutation carriers. Similarly, no association was found between the number of repeats and the fertilization rate, cleavage rate or biopsy rate among premutation carriers.

Limitations, reasons for caution: We had a relatively low number of premutation carriers with >100 repeats, which made it challenging to draw a firm conclusions from this group.

Wider implications of the findings: Physicians must address the increased risk for reduced ovarian response and primary ovarian insufficiency (POI) among carriers and consider surveillance of ovarian reserve markers. The last, might expedite family plans completion or fertility preservation.

Study funding/competing interest(s): None.

Keywords: CGG repeats; PGD; fragile X syndrome (FXS); premutation; primary ovarian insufficiency (POI).