Human tumors studied with genetic markers.

Genetic marker systems have been employed to investigate the origin and development of many human tumors. The type of information already gained with such systems includes the probable single cell origin of chronic myelocytic leukemia in a marrow stem cell. The G-6-PD system has also confirmed the hypothesis that at least some hereditary and viral tumors have multiple cell origin. However, Burkitt lymphoma, the malignancy in man for which there is a great amount of circumstantial evidence for a viral cancer, has a clonal origin. Of particular interest is the demonstration that early relapses after remissions of Burkitt lymphoma represent reemergence of the original malignant cell lines, whereas some late recurrences may be the result of newly induced malignant clones. Similarly, some recurrences of acute lymphoblastic leukemia in patients treated with marrow transplantation may be new occurrences of disease. These observations have important implications for the etiology and pathogenesis of Burkitt lymphoma and acute lymphoblastic leukemia.