A family history of prostate cancer is a consistent risk factor for prostate cancer, and can also be used to predict the presence of prostate cancer among asymptomatic men who undergo PSA screening. Approximately 5% of cases of prostate cancer have a familial component. The genetic epidemiology of prostate cancer is complex, and genes on chromosome 1 and X chromosome contribute to familial aggregation. Neither of these prostate cancer susceptibility genes have been identified, but are the subject of an active search. Hereditary prostate cancer resembles non-hereditary cancer in terms of age of onset, pathologic appearance and grade.