title: Calreticulin exon 9 mutations in myeloproliferative neoplasms.
abstract: BACKGROUND
  Calreticulin (CALR) mutations were recently discovered in patients with myeloproliferative neoplasms (MPNs). We studied the frequency and type of CALR mutations and their hematological characteristics.
  
  
  METHODS
  A total of 168 MPN patients (36 polycythemia vera [PV], 114 essential thrombocythemia [ET], and 18 primary myelofibrosis [PMF] cases) were included in the study. CALR mutation was analyzed by the direct sequencing method.
  
  
  RESULTS
  CALR mutations were detected in 21.9% of ET and 16.7% of PMF patients, which accounted for 58.5% and 33.3% of ET and PMF patients without Janus kinase 2 (JAK2) or myeloproliferative leukemia virus oncogenes (MPL) mutations, respectively. A total of five types of mutation were detected, among which, L367fs(*)46 (53.6%) and K385fs(*)47 (35.7%) were found to be the most common. ET patients with CALR mutation had lower leukocyte counts and ages compared with JAK2-mutated ET patients.
  
  
  CONCLUSIONS
  Genotyping for CALR could be a useful diagnostic tool for JAK2-or MPL-negative ET or PMF patients. CALR mutation may be a distinct disease group, with different hematological characteristics than that of JAK2-positive patients.
authors.affiliation: Department of Laboratory Medicine, Keimyung University School of Medicine, Daegu, Korea.
authors.forename: Jung-Sook
authors.initials: JS
authors.lastname: Ha
authors.affiliation: Department of Laboratory Medicine, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Yu-Kyung
authors.initials: YK
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D001483:Base Sequence; D037282:Calreticulin / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology; D053628:Receptors, Thrombopoietin / Q000235:genetics; D055815:Young Adult
chemical_list: D037282:Calreticulin; D053628:Receptors, Thrombopoietin; C082218:MPL protein, human; C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: Calreticulin; JAK2; MPL; Myeloproliferative neoplasm