The JAK2 exon 12 mutations: a comprehensive review

Am J Hematol. 2011 Aug;86(8):668-76. doi: 10.1002/ajh.22063. Epub 2011 Jun 14.


A variety of acquired mutations targeting JAK2 exon 12 are present in those patients with the myeloproliferative neoplasm, polycythemia vera, that lack the more common JAK2V617F mutation. Both mutation types perturb erythropoiesis, with individuals presenting with a raised hematocrit, reduced serum erythropoietin levels, and erythropoietin-independent erythroid progenitor cells. However, there are also phenotypic differences that, until recently, precluded a significant proportion of patients with a JAK2 exon 12 mutation from receiving an appropriate diagnosis. Here, we review the literature published on the JAK2 exon 12 mutations and compare the biology associated with these mutations with that of JAK2V617F.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Diagnosis, Differential
  • Erythropoiesis
  • Exons*
  • Humans
  • Janus Kinase 2 / chemistry
  • Janus Kinase 2 / genetics*
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation*
  • Polycythemia Vera / diagnosis
  • Polycythemia Vera / genetics
  • Polycythemia Vera / physiopathology
  • Protein Structure, Tertiary
  • Sequence Alignment


  • JAK2 protein, human
  • Janus Kinase 2