To account for the recognized predisposition risk for MPN driven by the JAK2 46/1 haplotype8, we computed two PGSMPN scores, separating rs1327494 (tagging the JAK2 46/1 haplotype; PGSMPN-46/1) from nontagging JAK2 variants (PGSMPN-other). The gene discussed is JAK2; the disease is myeloproliferative disorder.