Introduktion. Acute leukemias (AL) are characterized by different clinical courses and different sensitivity to therapy. Taking into consideration their significant prevalence, an intensive search for new prognostic criteria is conducted that may determine individual prognosis and define the most appropriate treatment approach for patients with AL. One of the most prognostically unfavorable rearrangements in AL is the Philadelphia (Ph) chromosome, resulting from the t(9;22)(q34;q11) translocation. The frequency of such rearrangement is 1-3 % in acute myeloid leukemia (AML), 15-30 % in acute lymphoblastic leukemia (ALL) and about 20 % in mixed-phenotype AL. 

Aim of the investigation was to detect diagnostic and prognostic significance of karyotype changes, in particular the Ph chromosome, in patients with AL. 

Materials and methods. Cytogenetic investigations of bone marrow and/or peripheral blood cells from 211 patients with AL was performed (range: 18-85 years, 113 males and 98 females). The method 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 Cytogenomic Nomenclature (2024). 

Results. Chromosomal abnormalities of various kinds were found in 58 % patients with AML and 67 % patients with ALL and mixed-phenotype AL. Taking into consideration the identified cytogenetic abnormalities patients were classified by risk groups: with unfavorable cytogenetic markers (26 %), without significant prognostic markers (57 %) and with favorable prognostic factors (17 %). All Ph-positive AL were classified to the risk group with unfavorable markers. The Ph chromosome was most frequently detected in ALL (21 %) and mixed-phenotype AL (17 %). 

Conclusions. The frequency of Ph chromosome in patients with AML, ALL and mixed-phenotype AL was 1 %, 21 % and 17 %, respectively. Patients with Ph chromosome were classified to the subgroup of AL with the worst prognosis. Additional abnormalities of various kinds were observed in 64 % of examined patients with Ph-positive ALL. Besides the analysis of differential banding pattern chromosomes for AL patients it is necessary to apply molecular genetic studies.

Keywords: acute myeloid leukemia, acute lymphoblastic leukemia, mixed-phenotype acute leukemia, karyotype, cytogenetic aberration, Philadelphia chromosome, diagnosis, prognosis.