Rs3782179

Testicular germ cell tumor risk I("TGCT"; i.e. testicular cancer risk) was increased 3x per copy of the major (T) allele at rs3782179 and rs4474514 (OR = 3.08, CI: 2.29–4.13; OR = 3.07, CI = 2.29–4.13, respectively), based on a genome-wide scan of 277 primarily Caucasian TGCT cases and 919 controls. Men who have two copies of the common version of the c-KIT ligand KITLG gene have a 4.5-fold higher risk of testicular cancer than men who have two copies of the less common or minor version of the gene.

https://www.23andme.com/you/community/thread/7837/ The original study was also only done in 277 people with the disease and 900 controls, so it's a very small study.