Of the chromosomal abnormalities associated with AML with increased marrow eosinophils (i.e., >5% marrow eosinophils), the best example is inv(16)(p13.1q22) or t(16;16)(p13.1;q22), resulting in the fusion of CBFB at 16q22 to MYH11 at 16p13.1 (CBFB-MYH11). The gene discussed is CBFB; the disease is acute myeloid leukemia.