JAK2 and essential thrombocythemia: Previous reports have frequently correlated JAK2 V617F allele burden with elevated hematocrit, leukocyte count and high complication rate in MPNs.38-42 Our results indicated no significant correlation between the allele burden and hemoglobin, leukocyte or platelet count for PV and PMF patients in agreement with some reports 8,33  but in ET group, the relationship between the JAK2 V617F allele burden and leukocyte count was significant.