Association of variants in genes involved in environmental chemical metabolism and risk of cryptorchidism and hypospadias.

We hypothesized that single-nucleotide polymorphisms (SNPs) of genes involved in environmental endocrine disruptors (EEDs) metabolism might influence the risk of male genital malformations. In this study, we explored for association between 384 SNPs in 15 genes (AHR, AHRR, ARNT, ARNT2, NR1I2, RXRA, RXRB, RXRG, CYP1A1, CYP1A2, CYP1B1, CYP2B6, CYP3A4, CYP17A1 and CYP19A1) and risk of cryptorchidism (CO) and hypospadias (HS) in 334 Japanese (JPN) males (141 controls, 95 CO and 98 HS) and 187 Italian (ITA) males (129 controls and 58 CO). In the JPN study group, five SNPs from ARNT2 (rs2278705 and rs5000770), CYP1A2 (rs2069521), CYP17A1 (rs4919686) and NR1I2 (rs2472680) were significantly associated at both allelic and genotypic levels with risk of at least one genital malformation phenotype. In the ITA study group, two SNPs in AHR (rs3757824) and ARNT2 (rs1020397) were significantly associated with risk of CO. Interaction analysis of the positive SNPs using multifactor dimensionality reduction demonstrated that synergistic interaction between rs2472680, rs4919686 and rs5000770 had 62.81% prediction accuracy for CO (P=0.011) and that between rs2069521 and rs2278705 had 69.98% prediction accuracy for HS (P=0.001) in JPN population. In a combined analysis of JPN and ITA population, the most significant multi-locus association was observed between rs5000770 and rs3757824, which had 65.70% prediction accuracy for CO (P=0.055). Our findings indicate that genetic polymorphisms in genes involved in EED metabolism are associated with risk of CO and HS.