Cytogenetic and molecular biological studies on atomic bomb related leukemias

The outcome of the previous cytogenetic and molecular-biological studies in leukemic A-bomb survivors is reviewed. In evaluable 75 A-bomb survivors with acute myelocytic leukemia (AML), the incidence of chromosome aberrations was significantly higher in the group exposed to one Gy or more than the other groups (100% vs 52.9% to 60.9%). The one Gy or more group was also characterized by having complicated abnormal karyotype. Molecular-biological studies for ras oncogene mutation in AML patients revealed no significant difference in either the incidence or site of mutation between the exposed and the non-exposed groups. For chronic myelocytic leukemia (CML), cytogenetic study revealed chromosome aberration specific to CML, such as Philadelphia chromosome t(9;22)(q34;q11), irrespective of exposed or non-exposed patients. Nor was there difference in bcr rearrangement between the exposed and non-exposed groups. These results suggest that transformation mechanism of radiation-induced leukemia may be different between AML and CML. (N.K.)