CYTOGENETIC INVESTIGATIONS OF LEUKEMIC CELLS AT DIFFERENT STAGES OF ACUTE LEUKEMIA

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Cytogenetic investigations of bone marrow (BM) and/or peripheral blood (PB) cells from 11 patients (range: 18–47 years, 6 males and 5 females) were performed at different stages of acute leukemia (AL): in newly diagnosed patients, in remission and at relapse. The methods of conventional cytogenetics (GTG) and fluorescence in situ hybridization (FISH) were used. Cytogenetic methods were performed using standard techniques and karyotypes were described according to the International System for Human Cytogenetic Nomenclature (ISCN, 2016). Structural (del(1)(q24), i(7)(q10), t(8;21)(q22;q22), del(9)(q21-q22), t(9;22)(q34;q11), t(15;17)(q22;q11-21), der(17)t(17;?)(р11;?), marker chromosomes) and numerical (trisomies, monosomies) chromosomal abnormalities were found. Some genetic abnormalities (BCR/ABL and PML/RARA fusion genes) were detected by molecular genetic methods (FISH). Spectrum of cytogenetic abnormalities had an important diagnostic and prognostic significance. Diagnosis of AL is possible due to the presence of specific genetic markers that can confirm some types of AL, namely t(8;21)(q22;q22) detect in patients with acute myeloid leukemia M2 (AML M2), t(15;17)(q22;q11-21) – in patients with acute promyelocytic leukemia (APL), t(9;22)(q34;q11) – in patients with acute lymphoblastic leukemia (ALL). Taking into consideration the identified cytogenetic abnormalities AL patients were classified by risk groups: the group of patients with adverse prognosis factors, the intermediate-risk group without significant prognostic markers and the group of patients with favorable cytogenetic markers. Distribution of patients into risk groups according to the identified prognostic markers allows to choose the most appropriate treatment approach for them, namely the intensity of therapy, the necessity of bone marrow transplantation in the first remission, the necessity of the prescription of tyrosine kinase inhibitors for patients with AL with t(9;22)(q34;q11) or differentiating agent – all-trans retinoic acid (ATRA) for patients with AML with t(15;17)(q22;q11-21). Thus, cytogenetic investigations should be included in the standard examination of patients with AL for diagnosis, prognosis and selection the optimal treatment strategy. Besides the analysis of differential banding pattern chromosomes it is necessary for patients with AL to apply molecular genetic studies, namely FISH and polymerase chain reaction (PCR).

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