The Status of JAK2 Mutations among Sudanese Patients with Polycythaemia Vera

Abstract

Abstract Background Primary polycythaemia or polycythaemia Vera is a myeloproliferative disorder characterized by increased red cell mass with low serum erythropoietin level. Ir1 recent years, a somatic point mutation in the Janus Kinase 2 (JAK2) gene (1849 G—>T,V6 17F) has been reported to occur in over 90% of patients with polycythaemia vera. Another JAK2 mutation in exon 12 had been described and ‘reported by researchers and the studies showed that JAK2 exonl2 mutations can activate erythropoietin signaling pathways.This mutations is now playing an important role in differentiating polycythaemia Vera fiom erythrocytosis. Furthermore, it may lead to a new therapeutic approach. Polymorphisms of P53 tumor suppressor gene are common in human cancers, and have been reported to be associated with the initiation and progression of myeloproliferative disorders. Objecfive I The purpose of this study was to determine the fiequency of JAK2V6l7F and JAK2 exon 12 mutation among Sudanese patients with polycythaemia Vera.The study also aimed to verify whether there is an association between P53 codon 72 Arginine\Proline polymorphism and polycythemia Vera among Sudanese patients or not Materials and methods A total of 84 patients with polycythaemia were enrolled in this cross sectional study 75 (89.3%) of them were males and nine (10.7%) were females.Their age range was between 23-80 years. Six milliliter (ml) of venous blood were collected from each patient, 3.0 ml in ethylene diarnine

tretraacetic acid (E.D.T.A) container for molecular analysis and 3.0 ml in a plain container for measurement of serum erythropoietin level using enzyme-linked immunoassay (ELISA). For molecular analysis DNA was extracted from EDTA anticoagulated blood sample by GF- IBLOOD DNA EXTRACTION KIT JAK2 V6l7F mutation was detected using Allele-specific competitive blocker (ACE)-PCR assay,JAK2 ex'on 12 mutation was detected by High Resolution Melting analysis technique and P53 codon 72 polymorphism was detected by Allele specific PCR assay. _ Results: A total of 83 patients attending the military hospital, and Khartoum teaching hospital, who presented with absolute erythroeytosis were enrolled in this study. Their ages ranged between 23=80 years (mean:+:SD: 39il.5). According to patients‘ history and the results of EPO level, nine (10.7 %) out of 84 patients were found to have secondary polycythaemia and 75 (89.3%) of patients had polycytbaemia Vera (PV). The frequency of JAK2 mutations (JAKV617F and exon 12) was 94.6%o in Sudanese patients with polycythaemia Vera. IAKZV6 17F was found in 91% and JAK2 exon 12 mutation in 8.1% of studied patients .the overall mean age of the studied group was 38 years while it was 41 years among those with JAK2V6l7F mutation and 36 years among those with JAK2 exon 12 mutation; this finding is consistent with published data which reported that PV is uncommon in individuals younger than 20 years. The mean of HCT was higher in patients positive for JAK2 exon 12 mutation than those positive for J'AK2V6l7F mutation (0.51 l/1 and 0.53 l/l respectively), mean of leucocyte count was higher in patients with JAK2V6l7F mutation than those positive for JAK2 exon I2 mutations. (7.39 and

6.7 X 10 9 / L respectively) and mean Platelets count was higher in patients with JAK2V6l7F mutation than those positive for exon 12 mutations (352 and 279X l0_ 9 / L respectively)._. The result- showed that,»Arg\Pro genotype was the most common among patients with polycythemia Vera, followed by Arg\Arg and Pro\Pro genotypes consequently. There was a significant association between Arg\Pro genotype and polycythemia Vera (O.R: 5.4, CI: 1.8- 16.2, P.value:0.001) ' 4 Conclusion In summary JAK2 V6l7F and JAK2 exon 12 mutations are detected in 94.6% of the studied Sudanese polycythaemia Vera patients. The data indicated and exemplified the importance of JAK2V617F and JAK2 exon 12 mutations analysis in a clinical laboratory for the diagnosis of PV.