Mutations in JAK2, Myeloproliferative Leukemia Virus (MPL), or Calreticulin (CALR) are detected in more than 80% of myeloproliferative neoplasm (MPN) patients, and these mutations are thought to play a significant role in the pathogenesis of MPN1–7. This evidence concerns the gene CALR and myeloproliferative neoplasm.