TET2 and essential thrombocythemia: Therefore, it is likely that clonal expansion occurs at later stages of differentiation elicited by other somatic mutations (i.e., TET2, DNMT3A). These mutations may cooperate with driver mutations to favor clonal dominance and may occur prior to JAK2V617F. Indeed, the chronological sequence of mutations affects disease phenotype, particularly for TET2 and DNMT3A: the acquisition of TET2 or DNMT3A prior to JAK2V617F mutation leads to an ET phenotype; by contrast, when JAK2V617F occurs first, it dictates a PV phenotype.