Evaluation of Janus kinase 2 exon 12 mutations in patients with JAK2V617F-negative polycythemia vera

Background and Objectives: Polycythemia vera (PV) is an acquired and clonal stem cell disorder characterized by abnormal erythropoiesis. The identification of a unique Janus kinase 2 (JAK2) gene mutation that leads to increased activity of the protein in patients with chronic myeloproliferative disorders has provided a beneficial diagnostic marker. In this study, we evaluated JAK2 exon 12 mutations in V617F-negative patients with PV.

Patients and Methods: We conducted a cross-sectional study of patients with PV who had been referred to Shariati Hospital (Tehran, Iran) between 2013 and 2016. We tested all samples for leukemia and cell line using flow cytometry. Additionally, the chromosomal karyotype of all samples was checked using metaphase culture. Lastly, DNASIS software was used to determine whether a mutation was present in the determined sequence. SPSS version 22.0 was used to analyze the data.

Results: Overall, 150 patients (average age: 46.30 ± 19.50 years) were included in this study. Of these patients, 12 (8%) were detected to carry JAK2 exon 12 mutations, including two novel mutations (NG_009904.1:g.89793T>G and NG_009904.1 (JAK2_i001)) that had not been previously reported. Among 23 patients, the average percentage of bone marrow blasts was 1.78 ± 0.95%. Moreover, out of 25 patients, three with increased erythropoiesis carried mutations in exon 12.

Conclusions: In addition to their diagnostic role in PV, the types of exon 12 mutations are clinically crucial. These findings and future studies on PV should provide better diagnostic and treatment methods for patients with the disorder.