title: Factor XII deficiency: a thrombophilic risk factor for retinal vein occlusion.
abstract: OBJECTIVE
  Factor XII deficiency is among the coagulation disorders that have been implicated in major thromboembolic events. However, little is known about an association of this coagulation disorder and retinal vessel occlusion. In the current study, we investigated the prevalence of factor XII deficiency in patients with retinal vein occlusion (RVO) with reference to age and cardiovascular risk factors.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  A cohort of 150 consecutive patients with central or branch retinal vein occlusion and 135 subjects matched for age and gender were prospectively screened for factor XII deficiency. Both cohorts were divided into two subgroups (<= 45 or >45 years), depending on the patients' age at the time of the RVO or a previous thromboembolic event.
  
  
  RESULTS
  Overall, factor XII deficiency was found to be present in 14 (9.3%) of 150 patients and in 1 (0.7%) of 135 controls (P =.0009). Patient age <= 45 years at the time of the RVO or a previous thromboembolic event was associated with a high prevalence of factor XII deficiency (18%). By contrast, only 5 (5%) of 100 patients >45 years (P =.016) and none of the young controls (P =.0001) tested positive for factor XII deficiency. The prevalence among patients >45 years was similar to that found in age-matched controls (2%; P =.66).
  
  
  CONCLUSIONS
  Our results indicate that factor XII deficiency is highly prevalent in RVO patients <= 45 years of age. By contrast, the prevalence of factor XII deficiency in RVO patients older than 45 years appears to be similar to that seen in healthy individuals.
authors.affiliation: Department of Ophthalmology, Klinikum der Johann-Wolfgang-Goethe-Universität, Frankfurt am Main, Germany. ckuhli@gmx.de
authors.forename: Claudia
authors.initials: C
authors.lastname: Kuhli
authors.forename: Inge
authors.initials: I
authors.lastname: Scharrer
authors.forename: Frank
authors.initials: F
authors.lastname: Koch
authors.forename: Christian
authors.initials: C
authors.lastname: Ohrloff
authors.forename: Lars-Olof
authors.initials: LO
authors.lastname: Hattenbach
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005174:Factor XII / Q000032:analysis; D005175:Factor XII Deficiency / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012170:Retinal Vein Occlusion / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors; D019851:Thrombophilia / Q000453:epidemiology*
chemical_list: D005174:Factor XII