The majority of studies failed to detect any association of the JAK2 haplotypeGGCC_46/1 with the distribution of age, sex or clinical parameters, including hemoglobin level, leukocyte count, rate of thrombosis/disease transformation and survival, suggesting that the JAK2 haplotypeGGCC_46/1 does not seem to affect the clinical phenotype or prognosis (Table 1) [12,19,20,43]. The gene discussed is JAK2; the disease is deep vein thrombosis.