Cytogenetic features of acute nonlymphoblastic leukemia in 73 children and adolescents.

We examined the leukemia cells of 81 consecutively admitted children and adolescents with acute nonlymphoblastic leukemia (ANLL) to determine the frequency and specificity of chromosomal abnormalities. Karyotypes were obtained for 73 (90%) of the 81 children, and 36 (49%) were abnormal. The modal karyotypes for the cases were tightly clustered in the diploid range; only 5 (7%) were hypodiploid, with 45 chromosomes each, and only 2 (3%) had greater than 50 chromosomes. Specific chromosomal abnormalities in the abnormal karyotypes were compared to morphologic subgroups of ANLL. An 8;21 translocation was found in 6 of 9 cases with M2 morphology but was also found in 1 case with M1 morphology. One of 4 with M3 (progranulocytic) morphology had a 15;17 translocation, and another had a 17q deletion. A structural abnormality in 11q was found in 3 of 7 patients with M5 (monoblastic) morphology, 2 of whom had a 9;11 translocation. The only case of M6 had a 22q-or Philadelphia chromosome in addition to other abnormalities. Statistical analysis of 27 abnormal karyotypes showed preferential structural rearrangement of 8q and 21q. We conclude that, in children as well as adults, specific structural abnormalities are correlated with certain morphologic subgroups of ANLL. However, other chromosomal changes associated with prior mutagenic exposure of adult ANLL were uncommon in children, which may suggest a difference in pathogenesis.