For some time, it has been known that there is a substantial genetic component to testicular germ cell tumour susceptibility, supported by several pieces of evidence, including the significantly increased familial risk and differential risk among races. However, despite extensive linkage searches on available families, no high penetrance genes have been identified. Recently genome-wide association studies have revealed three candidate loci, which confer up to a four-fold risk of developing TGCT. The genome-wide association studies for this cancer are noteworthy, because of the high effect sizes demonstrated at each loci and the biological plausibility of the genes at or near the associated SNPs, particularly KITLG.