with great interest we have read the recent article by Ernest et al. [1] reporting distinctive clinical and laboratory features of patients with Janus Kinase 2 (JAK2)-unmutated erythrocytosis. Considering that discriminating polycythemia vera (PV) patients from JAK2-unmutated patients is of major importance in everyday clinical practice, especially due to different treatment approaches, the study by Ernest et al. [1] provides valuable information for the practicing clinicians. It should be emphasized again that laboratory thresholds required for investigation of PV, a clonal hematopoietic stem cell disorder characterized by an increased thrombotic risk, have been significantly lowered in 2016 by the World Health Organization (WHO) [2], causing a substantial rise in PV investigations worlwide.
