Typical CBFβ/MYH11 fusion due to insertion of the 3′-MYH11 gene into 16q22 in acute monocytic leukemia with normal chromosomes 16 and trisomies 8 and 22

In a case of acute monocytic leukemia, M5a according to the FAB classification, with a 48,XY,+8,+22 karyotype, amplification of the CBFβ/MYH11 fusion transcript type A was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Fluorescence in situ hybridization (FISH) using an appropriate panel of DNA probes showed that insertion of the 3′-MYH11 within the CBFβ gene on chromosome 16q22 was the mechanism producing the same molecular rearrangement as in typical inv(16)(p13q22)/t(16;16)(p13;q22).