Cytogenetic studies on 519 consecutive de novo acute nonlymphocytic leukemias.

Cytogenetic studies were performed in the same laboratory on 519 untreated cases of de novo acute nonlymphocytic leukemia (ANLL) between 1977 and 1985. The overall incidence of clonal chromosome abnormalities was 54.3%; higher in children (67.5%) than in adults (50.4%). The distribution of chromosome abnormalities was uneven, according to the categories of the FAB nomenclature. The highest frequency of chromosome changes was observed in ANLL-M3 and the lowest in M1 and M6. The frequency of specific chromosome abnormalities and of their associated changes were also estimated. Monosomy 7 was detected in three patients with acute megakaryocytic leukemia (M7). Six cases with two abnormal chromosomally unrelated clones were observed and six constitutional chromosome abnormalities were detected. A clearer knowledge of the incidence of various chromosomal changes in ANLL seems necessary for better differentiation between the so-called primary and secondary chromosome abnormalities and for prognostic evaluation.