With the discovery of the JAK2V617F mutation in patients with Philadelphia chromosome-negative (Ph−) myeloproliferative neoplasms (MPNs) in 2005, major advances have been made in the diagnosis of MPNs, in understanding of their pathogenesis involving the JAK/STAT pathway, and finally in the development of novel therapies targeting this pathway. This evidence concerns the gene SOAT1 and myeloproliferative disorder.