JAK2V617F allele burden discriminates essential thrombocythemia from a subset of prefibrotic-stage primary myelofibrosis

Histopathological categories ET and prefibrotic PMF correlate with significant differences in mutant allelic burden of JAK2V617F, but not of MPLW515L which, by contrast to JAK2V617F, shows a higher percentage of mutated alleles in fibrotic than in prefibrotic cases. Thus, for Ph− MPN in which ET and prefibrotic PMF represent the most probable diagnoses, a JAK2V617F allele burden >50% favors a diagnosis of prefibrotic PMF.