Four out of 5 PV patients and 2 out of 2 ET patients carrying methylation of the SOCS3 promoter region were concurrently positive for the JAK2 V617F mutation and statistical analysis revealed that the presence/absence of JAK2 V617F mutation had no effect on the existence of SOCS3 promoter methylation (p>0.05). This evidence concerns the gene JAK2 and essential thrombocythemia.