Allelic Expression Imbalance of JAK2 V617F Mutation in BCR-ABL Negative Myeloproliferative Neoplasms

The discovery of a single point mutation in the JAK 2 gene in patients with BCR/ABL -negative myeloproliferative neoplasms (MPNs) has not only brought new insights and pathogenesis, but also has made the diagnosis of MPNs much easier. Although, to date, several mechanisms for the contribution of single JAK 2V617F point mutation to phenotypic diversity of MPNs have been suggested in multiple studies, but it is not clear how a unique mutation can cause the phenotypic diversity of MPNs. In this study, our results show that allelic expression imbalance of JAK 2 V617F mutant frequently occurs and contributes to phenotypic diversity of BCR-ABL -negative MPNs. The proportion of JAK 2 V617F mutant allele was significantly augmented in RNA levels as compared with genomic DNA differently by distinct MPNs subtypes. In detail, preferential expression of JAK2 mutant allele showed threefold increase from the cDNA compared with the genomic DNA from patients with essential thrombocythemia and twofold increase in polycythemia vera. In conclusion, allelic expression imbalance of JAK 2 V617F mutant proposes another plausible mechanism for the contribution of single JAK 2 point mutation to phenotypic diversity of MPNs.