JAK2 and myeloproliferative disorder: The major JAK2 mutation found in MPN patients is JAK2V617F (G1849T); therefore, epidemiological studies of MPN examining JAK2V617F have been greatly facilitated by PCR-based assays, such as ARMS (amplification refractory mutation system)-PCR [6], ABC (alternately binding probe competitive)-PCR [7], and allele specific (AS)-qPCR [8]–[11].