Genetic factors in malignant germ-cell tumors.

The etiology of germ-cell tumors is largely unknown. A history of undescended testis is the major known risk factor. Epidemiology studies have established the importance of (unknown) environmental factors probably operating very early in life. However, there are large differences in incidence in different populations and races. Familial cases and patients with bilateral cancer have been described, and the incidence is greatly increased in individuals with certain malformations of the urogenital system. The latter observations point to a genetic component in the disease's etiology. In most germ-cell tumors an isochromosome of the short arm of chromosome 12, i(12p), can be demonstrated. This highly characteristic cytogenetic aberration can be diagnostic of germ-cell tumors and may have prognostic importance. This article summarizes the current knowledge about and ongoing research on genes involved in the development of germ-cell tumors.