FMR1 Allelic Complexity and IVF Fertilization Success: Limitations and Future Perspectives

We investigated whether FMR1 allelic complexity-integrating CGG repeat length with the number and pattern of AGG interspersions-can be used as a predictor of ovarian reserve and in vitro fertilization (IVF) success. This cohort study included 124 females with infertility attributed to female factors undergoing intracytoplasmic sperm injection (ICSI). The total CGG repeat lengths and AGG interspersion patterns of the FMR1 gene were determined by conventional polymerase chain reaction (PCR) and triplet-primed PCR. The allelic complexity (allelic score) was calculated using a previously described formula by combining the allelic scores, allowing for the stratification of samples into equivalent and dissimilar groups. No statistically significant differences were observed in ovarian reserve markers or overall IVF outcomes between the two groups. However, within the dissimilar group, the allelic score of allele 1 was significantly correlated with the number of both injected metaphase II and two-pronuclei oocytes. These findings suggest that FMR1 allelic complexity may contribute to predicting IVF success, particularly in females classified in the dissimilar group, who appear more susceptible to IVF failure than those in the equivalent group. Further research into the predictive utility of FMR1 could provide valuable insights for fertility assessment and enhance assisted reproductive technologies.