title: The JAK2 V617F mutation in patients with cerebral venous thrombosis.
abstract: BACKGROUND
  It is currently unclear whether or not cerebral venous thrombosis, such as splanchnic venous thrombosis, can be the first manifestation of an underlying myeloproliferative neoplasm.
  
  
  OBJECTIVE
  To determine the prevalence of the JAK2 V617F mutation in patients with a first episode of cerebral venous thrombosis.
  
  
  METHODS
  In this retrospective cohort study, patients with cerebral venous thrombosis were tested for the JAK2 V617F mutation and were followed until the development of a myeloproliferative neoplasm or censored at the end of follow-up.
  
  
  RESULTS
  Ten of 152 patients (6.6%) carried the JAK2 V617F mutation. Three of them had known acquired risk factors for thrombosis, and five had thrombophilia. Six patients met the diagnostic criteria for myeloproliferative neoplasm at the time of cerebral venous thrombosis, and three additional patients developed the disease during the follow-up (median duration 7.8 years, range 6 months to 21.3 years), giving an annual incidence of 0.26% patient-years (95% confidence interval 0.05-0.64). The last patient has no evidence of disease after 3 years of follow-up. Patients without the JAK2 V617F mutation at the time of cerebral venous thrombosis were retested at the end of the follow-up and remained negative, with normal blood counts (log-rank test χ(2) : 159 [P<0.0001]).
  
  
  CONCLUSIONS
  Cerebral venous thrombosis can be the first symptom of a myeloproliferative neoplasm. Patients with cerebral venous thrombosis can carry the JAK2 V617F mutation, irrespective of blood count.
authors.affiliation: A. Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicina and Medical Specialties, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico and University of Milan, Milan, Italy.
authors.forename: S M
authors.initials: SM
authors.lastname: Passamonti
authors.forename: E
authors.initials: E
authors.lastname: Biguzzi
authors.forename: M
authors.initials: M
authors.lastname: Cazzola
authors.forename: F
authors.initials: F
authors.lastname: Franchi
authors.forename: F
authors.initials: F
authors.lastname: Gianniello
authors.forename: P
authors.initials: P
authors.lastname: Bucciarelli
authors.forename: D
authors.initials: D
authors.lastname: Pietra
authors.forename: P M
authors.initials: PM
authors.lastname: Mannucci
authors.forename: I
authors.initials: I
authors.lastname: Martinelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001777:Blood Coagulation / Q000235:genetics*; D016009:Chi-Square Distribution; D018572:Disease-Free Survival; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D020767:Intracranial Thrombosis / Q000201:enzymology / Q000235:genetics* / Q000401:mortality; D007558:Italy / Q000453:epidemiology; D053614:Janus Kinase 2 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000097:blood / Q000453:epidemiology* / Q000401:mortality; D010641:Phenotype; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D020246:Venous Thrombosis / Q000201:enzymology / Q000235:genetics* / Q000401:mortality; D055815:Young Adult
chemical_list: C507924:JAK2 protein, human; D053614:Janus Kinase 2