The group of PV included 95 (55%) patients with heterozygous JAK2V617F mutation, 64 (37%) with homozygous JAK2V617F mutation, 4 (2%) with JAK2 exon 12 mutation and 9 (5%) with non-mutated JAK2. Median follow-up from diagnosis was 5.4 (range 0.01–30.7) and 6.4 (0.01–30) years in ET and PV, respectively. Here, JAK2 is linked to essential thrombocythemia.