Introduktion. Myeloproliferative neoplasms (MPNs) have a high prevalence and genetic mutations play a role in their occurrence. MPNs are associated with clonal hematopoiesis, genomic instability, hemostasis dysregulation, and an altered immune response. Among the MPNs not associated with BCR-ABL1 mutations (Ph-negative/BCR-ABL1-negative MPNs) are polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). These diseases are caused by mutations in genes, such as the JAK2, CALR, and MPL genes, which participate in regulating the JAK-STAT signaling pathway. These mutant clones induce an inflammatory immune response that leads to immuno-thrombosis. Despite differences in disease type, MPNs are characterized by shared clinical, pathological, and molecular features. Clinical complications include an increased risk of arterial and venous thrombosis, varying degrees of constitutional symptoms caused by pro-inflammatory cytokines, splenomegaly, and a higher risk of progression to acute myeloid leukemia.

The aim  of this study was to ascertain the prevalence of JAK2 V617F, CALR exon 9 Type 1 (52 bp deletion) and Type 2 (5 bp insertion), MPL W515A/L/K/R-S mutations among a cohort of Ukrainian patients diagnosed with BCR-ABL1-negative MPNs. Determination of these mutations can be valuable in the screening, diagnosis, and treatment of patients.

Materials and methods. The present study included DNA samples from 763 patients with suspected BCR-ABL1-negative myeloproliferative diseases (including 430 cases of PV, 182 cases of ET, and 151 cases of PMF), admitted to the SI “Institute of Blood Pathology and Transfusion Medicine of NAMS of Ukraine” (Lviv, Ukraine) for genetic analysis between 2022 and 2024.

Mutations of JAK2 V617F, CALR, and MPL were analyzed using allele-specific polymerase chain reaction (PCR). GeneMAP™ kits manufactured by Genmark (Turkey) were utilized in the study. Molecular genetic analyses were performed using the CFX96™ Real-Time System (Bio-Rad, USA) and the geneMAP™ Viewer, according to established methodologies.

Results. According to our data, 44.04 % (336/763) of patients with Ph-negative MPNs had the JAK2 V617F mutation. The overall frequency of mutations in the CALR gene was 14.03 % (31/221): 9.50 % Type 1 CALR mutation (21/221) and 4.52 % Type 2 CALR mutation (10/221). MPL mutations were much less common: 2.11 % (4/190): 1.58 % MPL W515L (3/190) and 0.53 % MPL W515K (1/190).

Consistent with our studies, the JAK2 V617F frequencies in PV, ET, and PMF were 52.09 %, 35.16 %, and 31.79 %, respectively. The percentage of CALR mutant was 9.34 % in ET and 9.27 % in PMF, while the percentage of MPL mutant was 0.55 % in ET and 1.99 % in PMF.

Conclusions. Our results showed that the positive rate of driver mutations in patients with PV, ET, PMF was 52.09 %, 45.05 %, and 43.05 %, respectively, which significantly improved the diagnostic rate, especially in ET and PMF. Subsequently, these results were employed by hematologists for diagnostic purposes.

The present study offers significant insights into the characteristics of JAK2, CALR, and MPL mutations in BCR-ABL1-negative MPNs, underscoring the necessity of genetic characterization to optimize the clinical management of these diseases.

Keywords: JAK2 V617F; CALR; MPL; chronic myeloproliferative neoplasms; essential thrombocythemia; polycythemia vera; primary myelofibrosis.