title: Anti-prothrombin antibodies are associated with thrombosis in children.
abstract: BACKGROUND
  This investigation aimed to evaluate thrombotic risk factors in children, with special reference to autoantibodies against prothrombin and protein S.
  
  
  METHODS
  We studied 57 consecutive Swedish children and adolescents referred with a radiologically confirmed acute thrombotic event. Clinical data were collected and a thrombophilia investigation was performed, including analysis of autoantibodies against protein S (anti-PS) and prothrombin (anti-PT). The anti-PS and anti-PT autoantibodies were also investigated in sera from 47 healthy controls. Detection of autoantibodies was performed by quantitative enzyme-linked immunosorbent assays.
  
  
  RESULTS
  Results for anti-PT antibodies were positive in 21% (12/57) of the patients and 2.1% (1/47) of the controls (OR 12.0, 95% CI 1.7-534; p=0.005). Seven percent (4/57) of the patients and 2.1% (1/47) of the controls were positive for anti-PS antibodies (OR 3.4, 95% CI 0.3-174; p>0.30). The FV G1691A mutation was found in 25% (14/57), and 44% (25/57) had 2 or more prothrombotic risk factors. Sixty percent (34/57) of the thrombosis patients were female. Peaks in frequency of thromboembolic events were found in the neonatal and the adolescent periods. Fifty-three percent (30/57) had thrombosis in the lower venous system. Associated clinical conditions occurred in 91% (52/57): systemic illness in 31% (18/57), infections in 26% (15/57), and oral contraceptive use in 25% (14/57). Four percent (2/57) had no apparent clinical or prothrombotic risk factors.
  
  
  CONCLUSIONS
  This study suggests that anti-PT autoantibodies may be common risk factors for thrombosis in children, and it confirms the multifactorial nature of pediatric thrombosis.
authors.affiliation: Department of Clinical Sciences, Lund University, Malmö University Hospital, Malmö, Sweden. olof.rask@med.lu.se
authors.forename: Olof
authors.initials: O
authors.lastname: Rask
authors.forename: Andreas
authors.initials: A
authors.lastname: Hillarp
authors.forename: Erik
authors.initials: E
authors.lastname: Berntorp
authors.forename: Rolf
authors.initials: R
authors.lastname: Ljung
mesh_terms: D000293:Adolescent; D000888:Antibodies, Anti-Idiotypic / Q000235:genetics*; D001323:Autoantibodies / Q000097:blood* / Q000235:genetics; D016022:Case-Control Studies; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D015995:Prevalence; D017293:Protein S / Q000235:genetics*; D011516:Prothrombin / Q000235:genetics* / Q000276:immunology; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013927:Thrombosis / Q000453:epidemiology / Q000235:genetics*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D001323:Autoantibodies; D017293:Protein S; D011516:Prothrombin