Philadelphia-negative myeloproliferative neoplasms — focus on the JAK2V617F variant allele fraction

Advances in techniques used in cytogenetic-molecular diagnostics of blood malignancies allow for a better understanding of the mechanisms of the neoplastic process. The use of next-generation sequencing (NGS) or genome mapping for routine hematological diagnostics enables the assessment of the genetic change profile in hematopoietic cells, as well as insight into tumor clonality. One of the parameters used in such analysis is determining the variant allele fraction (VAF), which is the proportion of reads relative to the total number of reads at a genomic locus. One of the gene variants that has already found practical application in Philadelphia-negative myeloproliferative neoplasms (MPNPh-) is JAK2V617F. Assessing JAK2V617F VAF at time of diagnosis allows to confirm diagnosis of MPNPh-, but also to calculate of the risk of an unfavorable disease outcome (thrombotic risk and the risk of transformation to the fibrotic phase). Recent data indicate that JAK2V617F VAF monitoring is also usefulness in process of the therapy effectiveness monitoring in terms of molecular response