title: Design of a prospective neonatal cohort study of homozygous and double heterozygous factor V Leiden and factor II G20210A.
abstract: BACKGROUND
  Factor V Leiden (FVL) and Factor II (FII) G20210A represent common risk factors for thromboembolic (TE) events. In children, both venous and arterial TE-events have been associated with the presence of FVL and FII G20210A. In most heterozygous children with TE-events other prothrombotic factors can usually be identified. Case reports of children with homozygous FVL, including 3 patients described here, suggest that this genotype may convey a particulary high risk. However, prospective data about the type and frequency of TE-events in such children are lacking.
  
  
  METHODS
  We have initiated a prospective neonatal cohort study for the homozygous and double heterozygous genotypes for FVL and FII G20210A. The probands and the heterozygous controls are identified by neonatal screening that involves > 98% of the children born in Berlin and are followed up in a special out-patient clinic to document details of the clinical history, developmental parameters and the occurrence of TE-events.
  
  
  CONCLUSIONS
  This study will provide controlled and unbiased information about the clinical significance of the homozygous and double heterozygous genotypes of these mutations.
authors.affiliation: Humboldt University Berlin, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Hundsdoerfer
authors.forename: B
authors.initials: B
authors.lastname: Vetter
authors.forename: B
authors.initials: B
authors.lastname: Stöver
authors.forename: C
authors.initials: C
authors.lastname: Bassir
authors.forename: E
authors.initials: E
authors.lastname: Mönch
authors.forename: S
authors.initials: S
authors.lastname: Ziemer
authors.forename: A E
authors.initials: AE
authors.lastname: Kulozik
mesh_terms: D001778:Blood Coagulation Disorders / Q000150:complications* / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D005165:Factor V / Q000235:genetics*; D005260:Female; D005820:Genetic Testing; D005858:Germany; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D020767:Intracranial Thrombosis / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D010291:Paresis / Q000209:etiology; D011446:Prospective Studies; D011516:Prothrombin / Q000235:genetics*; D012107:Research Design; D013226:Status Epilepticus / Q000209:etiology
chemical_list: C095381:factor V Leiden; D005165:Factor V; D011516:Prothrombin