Primary myelofibrosis (PMF) is a type of myeloproliferative neoplasm characterized by the clonal proliferation of stem cells, often accompanied by mutations in Janus kinase 2 (JAK2), calreticulin (CALR), or myeloproliferative leukemia (MPL) genes (3). The gene discussed is JAK2; the disease is primary myelofibrosis.