Abstract
An acquired mutation in the Janus kinase 2 (JAK2) gene, V617F, is identified in subtypes of myeloproliferative neoplasms (MPNs) at high frequency and is one of the diagnostic criteria for MPNs. To detect the JAK2 V617F mutation, melting curve (MC) and amplification refractory mutation system (ARMS) assays have been developed. We first applied a dilution series of mutated DNA in wild-type DNA for each assay to determine the analytical sensitivities. The result showed that MC assay with inspection of the melting curves identified the mutated population at >5%, while ARMS detected the mutation with a limit of 1%. We next subjected DNA extracted from the peripheral blood in cases of MPN or other hematologic diseases to MC and ARMS assays. Of 11 cases of polycythemia vera (PV), all cases were positive for the mutation by both assays, including one with “mixed type” by MC but “mutant” by ARMS. Of 8 cases of essential thrombocytosis (ET), 5 by MC and 6 by ARMS showed the “mixed-type” pattern, while “mutant” cases were absent. One discordant case with ET,in which MC was negative but ARMS was positive, was estimated to contain a 3% mutated population at initial assay, while the percentage increased to 14.3% after 2 years. Two cases of myelodysplastic syndrome were mutation-positive. Our study showed that MC assay is sufficient to detect JAK2 V617F mutation in PV. However, high-sensitivity ARMS assay should be applied to ET, in which the mutated population may comprise a small fraction of the test material, when MC assay is negative.
