Impact of FMR1 Pre-Mutation Status on Blastocyst Development in Patients Undergoing Pre-Implantation Genetic Diagnosis

Abstract

Background/Aims: The study aimed to investigate the impact of fragile X mental retardation 1 (FMR1) pre-mutation status on blastocyst development in patients undergoing pre-implantation genetic diagnosis (PGD). Methods: Case-control study of patients <40 years undergoing PGD at blastocyst stage for FMR1 pre-mutation status. Age-matched patients undergoing PGD for other single gene disorders were considered controls. Blastocyst development, calculated per metaphase II (MII) oocyte retrieved and per 2 pronuclear (2PN) embryos, was compared between the 2 groups. Pregnancy outcomes after embryo transfer were also compared. Results: Eighty-one and 791 patients were included in the FMR1 and control groups, respectively. FMR1 pre-mutation carriers had lower indicators of ovarian reserve, required higher gonadotropin doses, and had fewer MII oocytes retrieved. Mean blastocyst development per MII oocyte (12.6 vs. 29.4%; p < 0.001) and per 2PN embryos (21.5 vs. 41.7%; p < 0.001) was lower in the FMR1 group. An inverse correlation between the number of FMR1 CGG repeats and blastocyst development per MII oocyte (ρ = -0.63; p < 0.001) was observed. There was no difference in the rates of clinical pregnancy, spontaneous abortion, or live birth among the groups. Conclusion: Our study suggests lower rates of blastocyst development in patients with FMR1 pre-mutation status and an inverse correlation between the number of FMR1 CGG repeats and blastocyst development.