The JAK2(V617F) tyrosine kinase mutation in blood donors with upper-limit haematocrit levels.
BACKGROUND
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.


METHODS
From the January 1, 2006 to December 31, 2006 all consecutive donors with a Hct above 50% if males (n=84) and 46% if females (n=19) underwent JAK2 mutation analysis. Seventy-nine donors (59 males and 20 females) whose Hct was normal at their last blood donation were randomly selected and used as controls.


RESULTS
Among the group of blood donors with a high Hct, we identified one donor who was positive for the JAK2 mutation. This man had a Hct of 50.6% at his last donation, while his average Hct in the preceding year was 51.7%. The prevalence of the JAK2 mutation could be estimated to be 1%, 0.6% or 0.02% in the three different populations considered: donors with a Hct level above the upper limit of normal, all tested donors or the entire donor cohort attending our transfusion service, respectively.


CONCLUSIONS
The present study suggests that apparently healthy subjects with repeatedly high levels of Hct may have the acquired mutation in JAK2. Laboratory screening tests for JAK2 may be offered to blood donors at transfusion services with expertise in molecular genetics.
Tagariello
Giuseppe
G
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
Di Gaetano
Rosanna
R
Sartori
Roberto
R
Zanotto
Daniela
D
Belvini
Donata
D
Radossi
Paolo
P
Risato
Renzo
R
Roveroni
Giovanni
G
Salviato
Roberta
R
Tassinari
Cristina
C
Toffano
Nunzio
N
D000328:Adult; D001782:Blood Donors; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D003937:Diagnosis, Differential; D005260:Female; D005820:Genetic Testing; D006400:Hematocrit; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D053614:Janus Kinase 2 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D010641:Phenotype; D011087:Polycythemia Vera / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D015995:Prevalence; D012189:Retrospective Studies
D053614:Janus Kinase 2