BACKGROUND: The diagnosis of BCR-ABL negative chronic myeloproliferative disorders (CMPD) according to WHO/PVSG criteria may be difficult. The V617F mutation has been reported in 65–97% of patients with polycythemia vera (PV), 23–57% with essential thrombocythemia (ET) and 35–57% with idiopathic myelofibrosis (IM). The value of JAK2 mutation in unclassifiable CMPD, idiopathic erythrocytosis (IE) and idiopathic thrombocythosis (IT) is unknown.

AIMS: We wished to evaluate the utility of the V617F screening in patients with known or suspected myeloproliferative diseases.

METHODS: We applied the screening assay for JAK2V617F described by

Baxter (Lancet 2005;365)
in 84 patients from our Clinical Department with a previous or suspected diagnosis of CMPD (retrospective and prospective cohort study). The variables were obtained from clinical records and the diagnosis were made according to WHO or PVSG criteria when was possible. There was: 14 cases of PV, 34 of ET, 14 of unclassifiable CMPD, 3 of IM, 13 of IT and 6 of secondary disorders.

RESULTS: The V617F screening was positive in 11/14 (79 %) of PV, 14/34 (41 %) of ET, 10/14 (71%) of unclassifiable CMPD, 3/3 IM, 1/13 (8%) of IT and 0/6 secondary disorders. At diagnosis, patients with mutation had significantly higher leucocyte and neutrophil counts and hemoglobin, hematocrit and LDH level. No significant interaction was noted between V617F mutation and the clinical data (gender, rates of transformation, splenomegaly, thrombosis and hemorrhage). The unclassifiable CMPD group was compared with the ET and PV groups. The unclassifiable CMPD group compared with the ET group showed a lower platelet count, a higher HCT level, and a higher frequency of JAK2 mutation.

CONCLUSIONS:

  1. In case of suspected CMPD the JAK2 mutation screening seems to be useful . Some patients with IT had the mutation and these patients may represent an early phase of ET.

  2. According to the literature the V617F mutation was associated with some laboratory parameters but we don’t find significant clinical associations.

  3. The JAK2 mutation is frequent in the unclassifiable CMPD and these patients had clinical features similar to the PV group.

  4. The WHO or PVSG criteria should be changed to incorporate the JAK2 screening to reach a higher sensibility.

Topics:
erythrocytosis, mutation, myeloproliferative disorder, chronic, screening, thrombocytosis, jak2 gene v617f, abnormal involuntary movement scale, alberta infant motor scales, bcr-abl tyrosine kinase, hemoglobin

Disclosure: No relevant conflicts of interest to declare.

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2006, The American Society of Hematology
2006
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