It is not rare to observe in blood donors a level of haematocrit (Hct) above or close to the highest normal limit. In the case of blood donors the diagnosis and clinical evaluation of this alteration may be complicated by regular blood donations that can mask an underlying disease such as polycythaemia vera. Recently a single acquired mutation in the Janus kinase 2 gene (JAK2) on chromosome 9 was identified and it was found that the incidence of this mutation was high in patients with polycythaemia vera.
Servizio Trasfusionale, Centro Regionale per le Malattie del Sangue ed Emofilia, Ospedale di Castelfranco Veneto e Montebelluna, Azienda ULSS 8 Regione, 31033 Castelfranco Veneto, Italy. giuseppe.tagariello@ulssasolo.ven.it
