Evaluation of genes associated with undescended testes as predictors of TGCT susceptibility.

Abstract

1539 Background: Testicular germ cell tumors (TGCTs) are highly heritable. Cryptorchidism (undescended testes; UDT) is a strong risk factor for TGCT, with increased risk to both the ipsilateral and contralateral testes. However, recent genome-wide association studies (GWAS) identifying genetic variants associated with TGCT susceptibility have not found differences in genotype carriage between TGCT patients with and without UDT. We investigated the role of potential risk variants for UDT as risk factors for TGCT. Methods: 1300 SNPs in and around 25 gene regions with published associations with UDT were evaluated in 474 TGCT cases (45 with UDT) and 919 controls. Genotype information was available from the Affymetrix Genome-Wide Human SNP Array 6.0. Statistical analysis was performed using PLINK, and statistical significance was assessed by Fisher's Exact test. Results: Comparing TGCT cases with and without UDT, variants in the region of four genes (EPHB2, ESR1, SEMA3C, TGFBR3) were suggestively associated with UDT. When TGCT cases with UDT were compared with unaffected controls, the associations all met the required level of significance (p < 4 x 10-5). Only variation at ESR1 approached significance (P=0.0004) when TGCT cases and unaffected controls were compared. Conclusions: We identified variants at three genetic loci - SEMA3C, TGFBR3 and EPHB2 - that were significantly associated with UDT, but not with TGCT. The association of variation in EPHB2 and SEMA3C with UDT are novel findings. While associated with UDT, variation at ESR1 is also potentially associated with TGCT risk. These data continue to suggest that genetic risk factors for UDT are largely independent of those for TGCT. Thus, screening for TGCT could be targeted in a UDT population to those with genetic risk factors. Further studies should be done to investigate the genetic link between UDT and TGCT.