['JAK2V617F mutation occurs in 90% of polycythemia vera (PV) and in 50% of essential thrombocythemia (ET) patients.', '253 consecutive patients affected by myeloproliferative disorders (MPD, 121 PV, 132 ET) were evaluated and stratified in 4 age groups: 18-39, 40-59, 60-75 and over 75 years (>75). The JAK2V617F mutation was searched and its allele burden was evaluated.', 'The percentage of mutated patients increased progressively with age mainly in patients >75 (p=0.0015 vs 18-39, p=0.0021 vs 40-59 and p=0.012 vs 60-75). We also found a progressive increase in allele burden with age (R2=0.042). Thrombotic events were more common in patients carrying the mutation in comparison with wild type (WT) (p=0.006, coefficient risk 1.94). No differences in the percentage of patients carrying the JAK2V617F mutation were found, in spite of different follow-up durations (<5 yrs, 5-10 yrs, 10-15 yrs, >15 yrs). The JAK2V617F allele burden was similar in patients with (57 ± 31%) and without (45 ± 26%) long-term hydroxyurea treatment.'] Is jAK2V617F mutation common in old patients with polycythemia vera and essential thrombocythemia?