BackgroundThe t(9;22)(q34;q11), generating the Philadelphia (Ph) chromosome, is found in more than 90% of patients with chronic myeloid leukemia (CML). As a result of the translocation, the 3' portion of the ABL1 oncogene is transposed from 9q34 to the 5' portion of the BCR gene on chromosome 22 to form the BCR/ABL1 fusion gene. At diagnosis, in 5-10% of CML patients the Ph chromosome is derived from variant translocations other than the standard t(9;22).ResultsWe report a molecular cytogenetic study of 452 consecutive CML patients at diagnosis, that revealed 50 cases identifying three main subgroups: i) cases with variant chromosomal rearrangements other than the classic t(9;22)(q34;q11) (9.5%); ii) cases with cryptic insertions of ABL1 into BCR, or vice versa (1.3%); iii) cases bearing additional chromosomal rearrangements concomitant to the t(9;22) (1.1%). For each cytogenetic group, the mechanism at the basis of the rearrangement is discussed.All breakpoints on other chromosomes involved in variant t(9;22) and in additional rearrangements have been characterized for the first time by Fluorescence In Situ Hybridization (FISH) experiments and bioinformatic analyses. This study revealed a high content of Alu repeats, genes density, GC frequency, and miRNAs in the great majority of the analyzed breakpoints.ConclusionsTaken together with literature data about CML with variant t(9;22), our findings identified several new cytogenetic breakpoints as hotspots for recombination, demonstrating that the involvement of chromosomes other than 9 and 22 is not a random event but could depend on specific genomic features. The presence of several genes and/or miRNAs at the identified breakpoints suggests their potential involvement in the CML pathogenesis.
In this study, we analysed the prognostic relevance of foetal liver tyrosine kinase 3 (FLT3) mutations in 73 patients with acute myeloid leukaemia (AML) with normal karyotype, who survived induction and consolidation and received autologous stem cell transplantation (ASCT) after successful mobilization of peripheral blood stem cell (PBSC). There were 44 males and 29 females with a median age of 54 years (range 20-77). Overall, 16 out of 73 autografted patients (22%) had FLT3 mutations. More in detail, FLT3/ITDs were detected in 10 out of 73 patients (14%), while FLT3 D835 mutations were detected in five cases (7%). One patient (1%) was found as having both abnormalities. White blood cell count (p=0.009), serum concentration of lactate dehydrogenase (p=0.01), and percentages of peripheral blood (p=0.002) and bone marrow blasts (p=0.03) were significantly higher in patients showing the FLT3 mutations. On the contrary, overall survival and disease-free survival were similar between patients with or without FLT3 mutations (p=0.73 and 0.78, respectively). In conclusion, our data suggest that myeloablative chemotherapy supported by auto-PBSCT may overcome the adverse prognostic implications of FLT3 mutations in AML. However, it is to consider that autografted patients are highly selected for best response to induction, consolidation and mobilization, as well as for minor non-haematologic toxicity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.