The Jak2V617F mutation, PRV-1 overexpression, and EEC formation define a similar cohort of MPD patients.

Recently, a Jak2V617F mutation has been described in the vast majority of patients with polycythemia vera (PV) as well as in subsets of patients with essential thrombocythemia (ET) and idiopathic myelofibrosis (IMF). The question arises whether this mutation is observed in those patients with ET and IMF who have also displayed previously described molecular markers, notably the ability to form endogenous erythroid colonies (EECs), overexpression of polycythemia rubra vera 1 (PRV-1), and decreased c-Mpl expression. We therefore analyzed the Janus kinase 2 (Jak2) DNA sequence, EEC growth, PRV-1 expression, and c-Mpl (myeloproliferative) levels in a cohort of 78 myeloproliferative disorder (MPD) patients (42 ET, 22 PV, and 14 IMF). Presence of the Jak2V617F mutation was very highly correlated with PRV-1 overexpression and the ability to form EECs in all 3 subtypes of MPDs (P < .001). (