What causes germ cell tumors?
The cause of germ cell tumors is not completely understood. A number of inherited defects also have been associated with an increased risk of developing germ cell tumors including the central nervous system and genitourinary tract malformations and major malformations of the lower spine. Specifically, males with cryptorchidism (failure of the testes to descend into the scrotal sac) have an increased risk to develop testicular germ cell tumors. Cryptorchidism can occur alone, however, and also is present in some genetic syndromes. In addition, cells from testicular germ cell tumors can have structural chromosome abnormalities involving chromosome 12, which may explain the uncontrolled cell growth and tumor formation. Some genetic syndromes caused by extra or missing sex chromosomes can cause incomplete or abnormal development of the reproductive system.