Polymorphism of the human Ha-ras oncogene locus in chronic lymphocytic and chronic myelogenous leukemia

DNA from white blood cells from healthy controls demonstrates a restriction fragment length polymorphism (RFLP) of the Ha-ras oncogene locus after cleavage with the restriction enzymes BamH I or MspI plus HpaII, representing frequent and rare alleles. We have studied the RFLP of 15 patients with B-cell chronic lymphocytic (CLL) and of 16 patients with chronic myelogenous leukemia (CML). As in healthy controls the RFLP in the leukemic cells indicates the occurrence of frequent and rare Ha-ras alleles. But rare alleles are not more frequent in the patients than in the healthy control group. The frequency of rare Ha-ras alleles also does not differ between chronic lymphocytic and chronic myelogenous leukemia. While rare alleles of this oncogene locus occur in CML and CLL as frequently as in healthy controls, they do not reflect an inherent increased risk for chronic leukemia in man.