JAK2Mutations in Myeloproliferative Disorders

Abstract
An activating somatic mutation involving the JH2 pseudokinase domain of Janus kinase 2 (JAK2 [V617F]) has been associated with myeloproliferative disorders. The mutation is detectable in 65 percent1 to 97 percent2 of cases of polycythemia vera. Kralovics and colleagues (April 28 issue)1 report a significant association between homozygosity for the JAK2 (V617F) mutation, which occurred in approximately one quarter of the patients with polycythemia vera, and increased duration of disease in polycythemia vera, essential thrombocythemia, and myelofibrosis with myeloid metaplasia. A similar observation was made by others,3 raising the possibility that homozygosity for the mutant allele is a time-dependent clonal evolution.