Reviews of chromosome studies in urological tumors. III. Cytogenetics and genes in testicular tumors.

PURPOSE: We reviewed available cytogenetic and molecular findings in testicular germ cell tumors, and their possible application to clinical, pathological and basic parameters.

MATERIALS AND METHODS: Findings in the literature on testicular germ cell tumors as well as those from our laboratory were summarized, including a listing of the cytogenetic findings on testicular germ cell tumors to date with some illustrations.

RESULTS: Testicular germ cell tumors are characterized in most cases by the presence of an i(12p) isochromosome. In tumors without such an abnormal chromosome studies using fluorescence in situ hybridization and molecular approaches have demonstrated either masking of the i(12p) or the presence of extra 12p sequences in the karyotype. Although testicular germ cell tumors are often associated with chromosome changes in addition to the i(12p), no other specifically recurrent structural chromosome changes have been found. Based on the cytogenetic and molecular findings in testicular germ cell tumors, a hypothetical scheme for the genetic events leading to these tumors is presented.

CONCLUSIONS: The genetic events leading to genesis of testicular germ cell tumors in men appear to be related to aneuploidization followed by the formation of an i(12p) isochromosome, the latter characterizing the preponderant number of testicular germ cell tumors. The exact role of the i(12p) isochromosome in testicular germ cell tumor pathogenesis remains to be determined, as is true of the genes involved in or affected by these tumors. Based on presently available information, a hypothetical pathogenetic and oncogenetic model for the development of testicular germ cell tumors is presented.