Uneven frequencies of secondary chromosomal abnormalities in acute myeloid leukemias with t(8;21), t(15;17), and inv(16).

The types and incidences of secondary chromosomal abnormalities were analyzed in three subtypes of leukemia with recurrent abnormalities, translocations t(8;21), t(15;17), and inversion inv(16). The main types of clonal secondary abnormalities were similar to those described in the literature, loss of sex chromosome associated with t(8;21), trisomy 8 with t(15;17), and trisomies 8 or 22 with inv(16). On the whole, the incidence of clonal abnormalities was significantly higher in t(8;21) leukemia than in the two other subtypes. This difference was not related to a chromosomal instability peculiar to this leukemia subtype, because the incidence of nonclonal abnormalities was the same in the three types of leukemia studied. The significance of secondary clonal abnormalities remains speculative. A careful comparative analysis of structural rearrangements of the chromosomes usually involved in secondary abnormalities must be carried out as a first step to identify the key genes altered.