Genetic Association of RXFP2 T222P Variant With Cryptorchidism: A Meta-Analytic Study

The RXFP2 receptor plays a key role in testicular descent, mediating the action of relaxin on gubernaculum development. The T222P polymorphism in the RXFP2 gene has previously been investigated in relation to cryptorchidism, but reported associations have been inconsistent across populations.

The aim of this meta-analysis was to assess the association of the T222P variant in the RXFP2 gene with the risk of cryptorchidism and to analyze effect-modifying factors, including population structure and allele frequencies in control groups.

A systematic literature review was conducted in PubMed, Embase, Web of Science, Scopus, and supplementary sources. Five studies with genotypic data for the T222P variant in case and control populations were selected. Allele and genotype frequencies were calculated, followed by cumulative OR values with 95% confidence intervals. Between-study heterogeneity was assessed using the I² statistic, and moderator analyses (Italy vs. other countries and P allele frequency in controls) as well as leave-one-out sensitivity analyses were performed. Study quality was assessed using the Newcastle-Ottawa Scale.

Carriers of the T222P variant showed a trend toward increased odds of cryptorchidism, with a more pronounced effect observed in Italian cohorts. Heterogeneity was moderate (I² ≈ 50%), and moderator analysis suggested that population differences and P allele frequency in controls may contribute to variability in effect estimates. Sensitivity analyses and alternative genotype models supported the consistency of the findings across analytical approaches.

The results support a potential association between the RXFP2 T222P variant and cryptorchidism risk, with population-specific effects likely reflecting underlying genetic background.

The RXFP2 T222P variant may be associated with an increased risk of cryptorchidism, but current evidence remains hypothesis-generating. Further studies in larger, ethnically diverse samples, with full genotyping and functional analysis, are needed to confirm and elucidate the mechanisms underlying the observed effect.