Background: Elevated JAK2V617F allele burden is associated with enhanced expression of downstream target genes in Philadelphia negative chronic myeloproliferative neoplasms (CMPNs) which include PV, ET & PMF. Previous studies have shown the impact of JAK2V617F allele burden on clinical phenotype of CMPNs. However, there is no data from India regarding the association between JAK2V617F allele burden and clinical phenotype in PV. Aims/Settings and Design: We aimed to investigate the effect of allele burden on clinical phenotype in 90 JAK2V617F positive PV patients and to see its influence on disease related complications. Material and Methods: Allele burden of 90 JAK2V617F positive PV patients was quantified by Real-time polymerase chain reaction (RQ-PCR). Results: 74/90 (82.22%) were males and 16/90 (17.78%) were females (median 45 years, range 35-78). Patients with age >50 years had significantly higher JAK2V617F allele burden (median 40.15%, range 0.49–91.62 %) than patients with ≤ 50 years age (median 48.59 %, range 0.56–86.74 %; P < 0.032). Patients with splenomegaly had significantly higher JAK2V617F allele burden (mean 50.24%, range 6.91–84.17%) than patients without splenomegaly (mean 33.82 %, range 0.49–71.83 %; P < 0.017). Patients with higher allele burden (median 57.20, range 43.4–72.03%) had significantly raised thrombotic events than the patients with lower allele burden (median 37.38, range 0.49–84.17% P < 0.043). 49/90 (54%) were homozygous and 41/90 (46%) were heterozygous. Conclusions: Higher JAK2V617F allele burden showed association with increased age, splenomegaly and thrombotic events. Thus, it may be considered for prognostication and setting up the treatment protocol in PV patients.

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Our study suggests that JAK2V617F mutation may increase the risk of thrombosis in CMPNs. This finding could lead to risk stratification, setting up the treatment strategy in CMPNs.

Chronic Myelogenous Leukemia (CML) is a myeloproliferative neoplasm characterized by proliferation of Philadelphia positive clonal pluripotent hematopoietic cells. Bleeding is a rare presentation of CML that can occur due to platelet dysfunction. Both pre-treatment and post-treatment platelet function abnormalities in CML have been described in the literature. We describe a rare case of childhood CML who presented with mucocutateous bleeding manifestations. On laboratory workup, a Glanzmann Thrombasthenia (GT) like platelet phenotype was demonstrated along with confirmation of diagnosis of CML in chronic phase. The acquired nature of platelet function defect was confirmed by demonstrating recovery of platelet antigens glycoprotein IIb/IIIa after achieving complete hematological response with Imatinib. Due to presenting complaint of bleeding diathesis and absence of hepatosplenomegaly, the case was undiagnosed for CML until the patient reported to us. Careful evaluation of complete blood counts, peripheral blood picture and detailed laboratory workup was the window to proper diagnosis and treatment in this case.

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