The Phenotype of JAK2 Exon 12-Mutated Myeloproliferative Neoplasms

While the majority of patients with polycythemia vera (PV) have an acquired JAK2 V617F mutation, a minority (< 5%) harbor alternative JAK2 mutations in exon 12 also predominantly associated with an erythroid phenotype. However, recent reports of JAK2 exon 12 mutations in patients with other myeloproliferative neoplasms suggest that this may not be the case. These findings have potential implications for molecular diagnostic algorithms.