Hereditary prostate cancer: A genetic form of prostate cancer. The risk of prostate cancer is clearly genetic. Men with a father or brother with prostate cancer are twice as likely to develop prostate cancer as men with no affected relatives. The risk increases with increasing number of affected relatives, such that men with 2 or 3 first-degree relatives affected have a 5-fold and 11-fold increased risk of prostate cancer, respectively. While most cases of prostate cancer appear not to be inherited as a simple single gene trait, some cases are.
There are two known patterns of simple Mendelian inheritance of prostate cancer. These patterns are autosomal dominant and X-linked. The first proof for the existence of a gene predisposing to prostate cancer was obtained in 1996. At that time a gene linked to an autosomal dominant form of prostate cancer was mapped to the long (q) arm of chromosome 1. The gene was called HPC-1 (hereditary prostate cancer 1). It has been located on the long (q) arm of chromosome 1 and mapped to region 1q24-q25. The gene encodes the enzyme ribonuclease L (RNASEL), a tumor suppressor. Germline (hereditary) mutations in this gene result in hereditary prostate cancer. Another gene responsible for hereditary prostate cancer has also been found on the X chromosome in region Xq27-28. The gene is called HPCX (hereditary prostate cancer on the X). Although these two genes (HPC1 and HPCX) account for but a fraction of all cases of prostate cancer, they are important and usher in the era of genetic testing for prostate cancer.