Dual color FISH on CBF primary acute myeloid leukemia

In acute myeloid leukemia (AML), clonal chromosomal aberrations constitute markers of diagnostic value and the molecular characterization of numerous abnormalities has greatly improved the understanding of the biology of distinct subtypes of the disease. Two of the most common recurring chromosomal abnormalities in AML are t(8;21) and inversion of chromosome 16 or its variant which belong to core binding factor (CBF) AML group. We aimed to compare between cytogenetics and dual color Fluorescence In Situ Hybridization (FISH) regarding their sensitivity for detection of CBF AML associated translocations including t(8;21) and inv(16)/t(16;16). Fifty five consecutive patients diagnosed as de novo AML were studied by chromosome banding analysis. Among them 32 patients were studied by FISH for the detection of AML1/ETO fusion gene and 11 patients for the detection of CBFbeta/MYH11. Four cases of AML (M2) subtype were positive for t(8;21) and 1 (M4) subtype was positive for inv(16) by karyotyping analysis. When FISH was applied 6 cases all of AML (M2) subtype were positive for t(8;21), 2 of them were of normal karyotype, and 5 cases all of M4EO subtype were found to be positive for inv(16)/ t(16;16) and 4 of them showed normal karyotypes. In conclusion, FISH can be used as a complementary technique to identify t(8;21) and inv16/t(16;16) in de novo AML as these abnormalities are difficult to diagnose in most cases by conventional cytogenetics alone.