A collaborative study of the relationship of the morphological type of acute nonlymphocytic leukemia with patient age and karyotype.

Data on the chromosome analysis of leukemic cells from consecutive patients with nonlymphocytic leukemia from six independent laboratories in the United States. Europe. and Australia were combined. The karyotypic pattern determined with banding was correlated with the patient’s age and the morphological type of leukemia according to the FAB classification. Of the 503 patients in the combined study. 260 had acute myeloblastic leukemia (AML. Ml and M2). 142 had acute myelomonocytic leukemia (AMMoL, M4). 43 had acute monocytic leukemia (AMoL. M5). 30 had erythroleukemia (EL. M6). and 28 had acute promyelocytic leukemia (API. M3). The percentage of patients with an abnormal karyotype was higher in EL (63%) and AMI (59%) than in AMMoL (40%) and AMoL (42%). In AML, the chromosome pattern showed a clear correlation with age. The consistent translocation involving nos. 8 and 21 . which is specifically associated with AML M2. occurred with the greatest frequency in younger patients. particularly those under the age of 45 yr. Other abnormalities. notably loss of no. 5 or part of its long arm. were not seen in children and showed a progressive increase in frequency with increasing age. Still other abnormalities. such as 7 or + 8. were present in all age groups. but were more common in older than in younger groups. In AMMoL. on the other hand. loss of no. 5 was rare. loss of no. 7 was less frequent in older than in younger patients. and gain of no. 8 showed some increase with age. Young patients with AMoL had either a