PB1954 DETECTION OF COMPLEX VARIANT T(9;22) CHROMOSOME TRANSLOCATIONS IN NEWLY DIAGNOSED CASES OF CHRONIC MYELOID LEUKAEMIA

Abstract

Background:Chronic myeloid leukemia (CML) is a stem cell clonal disease characterized by the acquisition of a fusion protein, BCR‐ABL1 oncogene, which leads to uncontrolled proliferation of myeloid elements in all stages of differentiation. However, a small proportion of patients with CML have simple or complex variants of this translocation, involving various breakpoints in addition to 9q34 and 22q11.Aims:Detection of complex variant t(9;22) chromosome translocations in newly diagnosed cases of Chronic Myeloid Leukaemia which help us to choose therapy modalities.Methods:This study was conducted for a time period of 05 years from 2012 to 2017 in the department of Oncology/ Hematology of Civil hospital, Karachi. Between April 2012 and April 2017, 88 CML patients were diagnosed in our Department. Informed consent was obtained from the patient in accordance with the Declaration of Helsinki. Diagnosis was done on the morphological basis and BCR‐ABL mutation by PCR/FISH. Conventional cytogenetic analysis was performed on unstimulated 24‐hour culture of a bone marrow (BM) specimen. The cells were cultured and processed by conventional methods, and the chromosomes were stained with trypsin‐Giemsa banding (GTG‐banding).Results:A total of 88 patients were Philadelphia‐positive CML, out of which 53(60.2%) were males & 35(39.7%) were females. Mean age was 48 yrs ± 11.43. Out of them, the group of 9 (10.2%) patients with complex cytogenetics were consisted of 5 females and 4 males, ranging in age at diagnosis from 32 to 66 yrs. All the patients were in chronic phase at presentation. Cytogenetic analysis by G‐banding revealed the presence of 9 reciprocal three‐way variant translocations of the classical t(9;22)(q34;q11). The chromosome breakpoints involved in these complex variant translocations were the following: 1p13, 1q21, 1p22, 2q31, 3q21, 3p21, 11q13, 15q24 and Xp11.2Summary/Conclusion:In our study 09 patients had complex variants of t(9;22).The presence of these complex variants at diagnosis and during the TKI treatment may announce treatment failure and/ or transformation to advanced stage (accelerated or blast). Early identification of these abnormalities may help in choosing therapy modalities.