Acute Myeloid Leukemia with Inv(16) Produces a Chimeric Transcription Factor with a Myosin Heavy Chain Tail

The M4Eo subtype of acute myeloid leukemia (AML) is a variant characterized by an increased number of morphologically abnormal eosinophils in bone marrow and peripheral blood, in addition to the accumulation of immature blasts common to all acute leukemias (Bennett et al. 1985). It constitutes about 8% of AML (Mitelman and Heim 1992). The leukemic cells of most M4Eo patients are characterized by a pericentric inversion of chromosome 16 (inv[16][p13;q22]) (Arthur and Bloomfield 1983; Le Beau et al. 1983), although other chromosome 16 abnormalities involving p13 and q22, e.g., t(16;16)(p13;q22), are also occasionally seen (Hogge et al. 1984; Testa et al. 1984; Holmes et al. 1985; Larson et al. 1986). Given the absence of other karyotypic abnormalities in many of these patients, a pathogenic relationship between inversion 16 and the M4Eo leukemia has been suggested.