Mutations outside exon 10 of MPL and exons 12 and 14 of JAK2 identified in triple-negative ET and PMF. (A) Somatic mutations in MPL identified in 4 cases of ET and 1 case of PMF. A common polymorphism is marked with the blue triangle. (B) Germline mutations in MPL identified in single cases of ET and PMF. (C) Germline JAK2 mutations found in 3 cases of triple-negative ET. Red boxes in panels A-C represent the amino acid change; black arrows indicate mutated bases. GRN, granulocyte; PT, patient; Ref, reference. (D) Schematic representation of the thrombopoietin receptor and the positions of mutations identified in triple-negative ET and PMF. Somatic mutations are indicated in red. (E) Schematic representation of the JAK2 kinase and the mutations found in ET. Black stars (★) in panels D and E indicate positions of MPL-W515K and JAK2-V617F, respectively.