JAK2 and acquired polycythemia vera: Those MPNs with positive JAK2 V617F mutation were associated with higher mean age (55.9 years vs 49.1 years), more female (49.2% vs 44.6%), more Malay ethnic (48.1% vs 37.8%), more PV (46.6% vs 22.1%), more vasomotor symptoms (23.9% vs 16.2%), more AT (23.1% vs 12.6%), more VT (4.4% vs 1.8%) than those MPNs with negative JAK2 V617F mutation (Table 1).