JAK2 and myeloproliferative neoplasm: Subsequently, ARMS-PCR assay was used to screen for V617F, whereas Sanger sequencing was used for the screening of mutations within exon 12 of Jak2. We observed that 42 (40%) were negative for V617F mutant and 63 out of 105 (60%) MPN cases harboured Jak2 V617F mutation.