BackgroundTo analyze the frequency of atypical fluorescence in situ hybridization signal patterns and estimate the complete cytogenetic response (CCyR) and major molecular response (MMR) during 12 months of tyrosine kinase inhibitor therapy in patients with newly diagnosed chronic myeloid leukemia.MethodsThe study included bone marrow and peripheral blood samples from 122 patients with newly diagnosed chronic myeloid leukemia. Detection of the breakpoint cluster region—Abelson fusion gene (BCR-ABL1) was performed using fluorescence in situ hybridization with a dual-color dual-fusion translocation probe, and MMR analysis was performed using the real-time quantitative polymerase chain reaction method.ResultsVariant translocation was determined in 10 samples and a deletion on the derivative chromosome 9 (del/der(9)) was found in 20 samples. The rates of CCyR and MMR were similar between patients with reciprocal translocation, variant translocation, deletion of derivative BCR, or ABL1-BCR fusion gene. The Kaplan-Meier test did not show any significant differences in the rates of CCyR and MMR among those groups of patients.ConclusionThe frequencies of variant translocation and del/der(9) in the present study agree with the results of other studies performed worldwide. No differences were observed in the rates of CCyR and MMR between patients with atypical patterns and reciprocal translocation.

Aim: Chronic myeloid leukemia (CML) is characterized by the Philadelphia (Ph) chromosome created by the reciprocal translocation t(9;22)(q34;q11), resulting in the hybrid gene breakpoint cluster region-Abelson (BCR-ABL1). Around 5-10% of CML cases develop complex variant Ph translocations involving one or more chromosomal regions besides 9 and 22. In this study we report a case of acute lymphoblastic leukemia (ALL) developed from CML displaying a novel four-way translocation. Case report: A complete blood analysis of a 46-yearold male patient showed an increase in white blood cells, lower levels of red blood cells and platelets. Bone-marrow sample was subjected to the conventional cytogenetic (Giemsabanding) and fluorescence in situ hybridization methods and the four-way translocation was identified. Considering hepatosplenomegaly and breakpoint cluster region that was characterized as major (M-bcr) on the quantitative real-time polymerase chain reaction (RQ-PCR), ALL was diagnosed as a transformation from CML. Conclusion: This study reports a new four-way translocation ins(22;1)(q11.2;q31q32)t(1;9;12;22)(q32;q34;q13;q11.2) in an ALL patient developed from the CML and was cross-checked in Mitelman Database of Chromosome Aberrations and Gene Fusions in Cancer.

Cilj: Obilježje kronične mijeloične leukemije (KML) je hibridni BCR-ABL gen nastao kao posljedica recipročne translokacije između kromosoma 9 i 22, čime se stvara Philadelphia (Ph) kromosom. Klasičnu translokaciju t(9;22) ima 90 % pacijenata, dok ostalih 5 – 10 % ima varijantnu translokaciju koja uključuje više kromosoma, izuzev kromosoma 9 i 22. Cilj ovog istraživanja je odrediti postotak pacijenata s novodijagnosticiranim KML-om koji imaju varijantnu translokaciju te postotak kompletnog citogenetičkog odgovora (KCgO) pacijenata s varijantnom translokacijom u usporedbi s pacijentima koji imaju klasičnu t(9;22). Materijali i metode: U istraživanje je uključena koštana srž (KS) 177 pacijenata s novodijagnosticiranim KML-om. Za analizu Ph kromosoma koristio se kariogram kao klasična citogenetska analiza i fluorescentna in situ hibridizacija (FISH) kao molekularna citogenetska analiza. Rezultati: Varijantna translokacija dokazana je kod 14 pacijenata u razdoblju od 5 godina i 3 mjeseca, dok 163 pacijenta ima klasičnu translokaciju t(9;22). Zaključak: Postotak pacijenata s varijantnom translokacijom u istraživanju slaže se s rezultatima istraživanja u svijetu. Ne postoji statistički značajna razlika u postizanju KCgO-a kod pacijenata s varijantnom translokacijom t(9;22) u usporedbi s KCgO-om pacijenata s klasičnom translokacijom.