关于双胞胎和非特异性基因缺陷的研究证据仍然不确定。
但是父子型FHx显示风险增加了10倍,并且至少3个研究结果显示睾丸癌在儿子身上出现更早。[18]Richiardi L, Akre O, Montgomery SM, et al. Fecundity and twinning rates as measures of fertility before diagnosis of germ-cell testicular cancer. J Natl Cancer Inst. 2004;96:145-147.http://jnci.oxfordjournals.org/content/96/2/145.fullhttp://www.ncbi.nlm.nih.gov/pubmed/14734704?tool=bestpractice.com[19]Dong C, Lonnstedt I, Hemminki K Familial testicular cancer and second primary cancers in testicular cancer patients by histological type. Eur J Cancer. 2001;37:1878-1885.http://www.ncbi.nlm.nih.gov/pubmed/11576844?tool=bestpractice.com[20]Dieckmann KP, Pichlmeier U. The prevalence of familial testicular cancer: an analysis of two patient populations and a review of the literature. Cancer. 1997;80:1954-1960.http://www.ncbi.nlm.nih.gov/pubmed/9366298?tool=bestpractice.com
睾丸癌发生风险从高到低分别是同卵双生、异卵双生、兄弟和父子。[18]Richiardi L, Akre O, Montgomery SM, et al. Fecundity and twinning rates as measures of fertility before diagnosis of germ-cell testicular cancer. J Natl Cancer Inst. 2004;96:145-147.http://jnci.oxfordjournals.org/content/96/2/145.fullhttp://www.ncbi.nlm.nih.gov/pubmed/14734704?tool=bestpractice.com[19]Dong C, Lonnstedt I, Hemminki K Familial testicular cancer and second primary cancers in testicular cancer patients by histological type. Eur J Cancer. 2001;37:1878-1885.http://www.ncbi.nlm.nih.gov/pubmed/11576844?tool=bestpractice.com[20]Dieckmann KP, Pichlmeier U. The prevalence of familial testicular cancer: an analysis of two patient populations and a review of the literature. Cancer. 1997;80:1954-1960.http://www.ncbi.nlm.nih.gov/pubmed/9366298?tool=bestpractice.com