title: [Clinical and biological features of patients with essential thrombocythaemia according to their mutational status JAK2 or CALR: Single-center study of 40 patients and review of the literature].
abstract: BACKGROUND
  Somatic mutations in the calreticulin gene (CALR) were recently described in essential thrombocythemia (ET) and primary myelofibrosis with non-mutated JAK2 or MPL. The aim of this single-center study was to compare the clinical and biological features of ET patients according to their mutational status.
  
  
  METHODS
  We included 40 patients with ET followed in hematology consultation. The JAK2 V617F mutation was assessed by quantitative PCR. For the detection of CALR mutations, we performed a PCR amplification of CALR exon 9 followed by direct sequencing.
  
  
  RESULTS
  Among 40 study patients, 23 (57.5%) harbored V617F JAK2, 12 of the 17 patients without JAK2 mutation harbored CALR, no patient expressed MPL mutation and 5 were negative for all three mutations. Five types of mutations were identified with predominance of 52bp deletion and 5bp insertion (7/12 and 2/12 respectively). The incidence of thrombotic events at diagnosis was significantly higher in JAK2 mutated patients (P<0.05). Biologically, patients with CALR mutation had significantly higher platelet count (P<0.01) and significantly lower hemoglobin level (P<0.05) than those with V617F JAK2 mutation.
  
  
  CONCLUSIONS
  JAK2 and CALR mutation screening in ET has a diagnostic value. Each mutation displays a distinct phenotype with uncertain impact on long-term outcome.
authors.affiliation: Service d'hématologie biologique, hôpital européen Georges-Pompidou, AP-HP, 20, rue Leblanc, 75908 Paris cedex 15, France. Electronic address: mehdi.bsaid@yahoo.fr.
authors.forename: M
authors.initials: M
authors.lastname: Ben Said
authors.affiliation: Service d'hématologie biologique, hôpital européen Georges-Pompidou, AP-HP, 20, rue Leblanc, 75908 Paris cedex 15, France; Inserm UMR-S1140, université Paris Descartes, 75270 Paris cedex 06, France. Electronic address: sophie.gandrille@univ-paris5.fr.
authors.forename: S
authors.initials: S
authors.lastname: Gandrille
authors.affiliation: Service d'hématologie biologique, hôpital européen Georges-Pompidou, AP-HP, 20, rue Leblanc, 75908 Paris cedex 15, France. Electronic address: anne-marie.fischer@egp.aphp.fr.
authors.forename: A M
authors.initials: AM
authors.lastname: Fischer
authors.affiliation: Service d'hématologie biologique, hôpital européen Georges-Pompidou, AP-HP, 20, rue Leblanc, 75908 Paris cedex 15, France. Electronic address: luc.darnige@egp.aphp.fr.
authors.forename: L
authors.initials: L
authors.lastname: Darnige
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D037282:Calreticulin / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D018740:Genetic Heterogeneity; D005838:Genotype; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D020125:Mutation, Missense; D010641:Phenotype; D017354:Point Mutation; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D013920:Thrombocythemia, Essential / Q000235:genetics*; D055815:Young Adult
chemical_list: C576483:CALR protein, human; D037282:Calreticulin; C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: CALR mutation; Essential thrombocythemia; JAK2 mutation; Mutation CALR; Mutation JAK2; Myeloproliferative disorders; Syndromes myéloprolifératifs; Thrombocytémie essentielle; Thrombose; Thrombosis