Mutations in INSL3 and RXFP2 genes in cryptorchid boys.

Mutations in the INSL3 and RXFP2 genes have been associated with human cryptorchidism but with contrasting data. We analyzed the frequency of mutations in these genes in 600 newborns with cryptorchidism (396 unilateral and 204 bilateral) and 300 noncryptorchid subjects. We found five RXFP2 mutations in five bilateral cryptorchid boys, one INSL3 mutation in a unilateral cryptorchid boy, and one INSL3 mutation in a boy with unilateral cryptorchidism at birth and spontaneous descent during the first month of life. Overall, the frequency of INSL3 and RXFP2 mutations was therefore 7/600 at birth (1.2%) and 7/303 (2.3%) in persistent cryptorchid boys, with a higher prevalence of bilateral forms (5/120, 4.2%). No mutations were found in controls. This study confirmed the association between INSL3 and RXFP2 gene mutations and human cryptorchidism.