CBFB and acute myeloid leukemia: In the AML M4 subtype with eosinophilia (AML M4Eo), which occurs in 5–9% of AML cases, a pericentric inversion inv(16)(p13q22) fuses CBFB (core-binding factor, beta subunit) at 16q22 with MYH11 at 16p13, forming the oncogenic CBFB::MYH11 fusion gene.