JAK2 and Splenomegaly: In MPN patients harbored the risk alleles of rs12343867C (JAK2 46/1) and rs12339666T (JAK2 intron 8), more patients were found to have splenomegaly at diagnosis (C vs T: 60% vs 40%, P = 0.007; T vs G: 61% vs 39%, P = 0.011, respectively), and fewer patients had overall hemorrhagic complications (C vs T: 36% vs 64%, P = 0.007; T vs G: 38.6% vs 61.4%, P = 0.012, respectively) (Supplementary Table 2).