Characterization of a new case of variant translocation t(9;22) in chronic myeloid leukemia by fluorescence in situ hybridization (FISH)

Abstract

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an occurrence of 1-2 cases per 100,000 subjects . Central to the pathogenesis of CML is the fusion of the "Abelson murine leukemia (ABL1) gene" on chromosome 9 with "the breakpoint cluster region (BCR) gene" on chromosome 22. This leads to expression of an oncoprotein called "BCR-ABL1".  In this study a new CML case carrying variant Philadelphia(Ph) translocation involving both chromosomes 9 and 22 as well as chromosomes 3 has been reported. A detailed molecular cytogenetic characterization was performed by fluorescence in situ hybridization (FISH), which displayed the presence of the"5'BCR/3'ABL1 "fusion gene was localized on the" Ph chromosome", while the" 5'ABL1/3'BCR gene "was not detected on the derivative(9) chromosome (der9) because 3'BCR translocated onto partner chromosomes 3.In conclusion, a precise molecular cytogenetic characterization of one Ph CML case bearing complex t(9;22)has been analyzed . The study also stress the crucial role of FISH analysis in explanation these translocations, which is beyond the resolution power of conventional cytogenetics.