Susceptibility Alleles for Testicular Germ Cell Tumor

A family history of Testicular Germ Cell Tumor (TGCT) is among the strongest and most well-documented risk factors for TGCT (Forman et al. 1992; Westergaard et al. 1996; Heimdal et al. 1996; Sonneveld et al. 1999; Hemminki and Li 2004). In a proportion of cases (∼2%), a first-degree family member is also affected with the disease (Forman et al. 1992). The relative risk to a brother of a TGCT case is 8–10 and between fathers and sons is 4–6 (Forman et al. 1992; Heimdal et al. 1996; Hemminki and Li 2004). This relative risk is higher than for most other cancer types, which are commonly 2 and rarely exceed 4 (Dong and Hemminki 2001). The high relative risk suggests that susceptibility genes are involved in the etiology of TGCT, which cannot be accounted for solely by shared environmental factors.