JAK2 and acquired polycythemia vera: In contrast to these three studies, which show that, in a diseased subject, platelet-specific expression of miR-26b-5p is lower, a study focusing on polycythaemia vera, a clonal haematopoietic stem cell disorder due to a mutation in Janus kinase 2 (JAK2), showed that miR-26b-5p is upregulated in diseased platelets [20].