JAK2 and myeloproliferative disorder: According to the International Working Group for myeloproliferative neoplasm (MPN) Research and Treatment (IWG-MRT) [22], the revised risk stratification scheme (revised IPSET-thrombosis model, R-IPSET) include four categories: ‘very low risk' (no thrombosis history, age < 60 years and JAK2-wide type); ‘low risk' (no thrombosis history, age < 60 years and JAK2-mutated); intermediate risk' (no thrombosis history, age > 60 years and JAK2-wide type) and high risk (thrombosis history or age > 60 years with JAK2 mutation).