Screening for Janus kinase-2 exon 12 mutations among Janus kinase-2 V617F-negative polycythemia vera suspected Iraqi patients

Abstract

Abstract: BACKGROUND: Diagnosis of myeloproliferative neoplasms including polycythemia vera (PV) has been greatly improved following the identification of driver mutations at exon 12 and exon 14 of the Janus Kinase 2 (JAK2) gene. There are limited academic studies that report the frequency of the JAK2 exon 12 gene with limited number of patients. OBJECTIVES: The aim of this study was to evaluate the frequency of JAK2 exon 12 mutations among JAK2V617F-negative PV-suspected Iraqi patients. PATIENTS’, MATERIALS AND METHODS: This is a retrospective study conducted at the National Center of Hematology/Mustansiriyah University from December 2019 to January 2022; patients with suspicion of PV were enrolled in this study. Screening for JAK2 exon 14 (JAK2V617F) mutations was done for all 323 patients. Out of them, there were 102 patients with JAK2V617F-negative who retrospectively screened for JAK2 exon 12 mutations by direct sequencing (Sanger sequencing). RESULTS: Initial evaluation for the total 323 patients suspected with PV revealed that 84 cases were mutated for the JAK2V617F gene, and 239 were unmutated. The frequency of JAK2 exon 12 was about 1% among JAK2V17F-negative patients. The median age for all patients was 35 years. Among the total cases, 21 cases (20.59%) showed splenomegaly at the time of clinical onset sequencing of these cases revealed only one case mutated with JAK2 exon 12 (E543-D544del). CONCLUSION: The current study showed that the frequency of JAK2 exon 12 mutations in JAK2V617F-negative cases was very low. Despite PV patients with JAK2 exon 12 mutations represent a small proportion of total PV cases, JAK2 exon 12 mutations should be routinely screened in JAK2V617F-negative cases.