title: A deep vein thrombosis caused by 20209C>T mutation in homozygosis of the prothrombin gene in a Caucasian patient.
abstract: BACKGROUND
  Additional nucleotide substitutions in the 3'-untranslated region of prothrombin gene could explain some thrombotic events and also adverse pregnancy outcomes. We describe the first case of a homozygous 20209C>T mutation as the cause of deep vein thrombosis in a Spanish patient.
  
  
  METHODS
  The 56-year-old male patient with a partial tear of the Achilles tendon developed calf (tibial) deep vein thrombosis after immobilization and was treated with an anticoagulant. To determine if the deep vein thrombosis was of genetic origin, a peripheral blood DNA sample was analysed for the presence of the three most frequent mutations associated with thrombotic events: factor V Leiden (1691G>A), prothrombin (20210G>A) and methylene tetrahydrofolate reductase (677C>T). The presence or absence of the normal allele of prothrombin could not be determined using the PTH-FV-MTHFR StripAssay (Vienna Lab).
  
  
  RESULTS
  Comprehensive analysis showed that the patient had a variant interfering with the polymerase chain reaction product, we sequenced the entire prothrombin gene and found that the patient had a homozygous C>T mutation at position 20209; this interfered with the polymerase chain reaction product, which needs a C at this position to be able to bind to the wild-type probe present in the test strip.
  
  
  CONCLUSIONS
  The homozygous 20209C>T mutation and the presence of the mutation 677C>T in heterozygosity explained the patient's deep vein thrombosis because the combination of mutations would increase the risk of thrombosis. Suitable genetic counselling should be provided to the patient and first-degree relatives as it important to detect prothrombin gene variants that could increase risk for thrombotic events.
authors.affiliation: Sección de Genética, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain.
authors.forename: Silvia Izquierdo
authors.initials: SI
authors.lastname: Alvarez
authors.affiliation: Sección de Genética, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain ; Facultad de Medicina. Universidad de Zaragoza, Spain.
authors.forename: Eva Barrio
authors.initials: EB
authors.lastname: Ollero
authors.affiliation: Departamento de Hematología, Hospital de Barbastro, Huesca, Spain.
authors.forename: Francisco Miguel
authors.initials: FM
authors.lastname: Llinares Sanjuan
authors.affiliation: Sección de Genética, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain.
authors.forename: Fabiola Lorente
authors.initials: FL
authors.lastname: Martínez
authors.affiliation: Sección de Genética, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Calvo Martín
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D005165:Factor V / Q000235:genetics; D005260:Female; D006720:Homozygote; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011516:Prothrombin / Q000235:genetics*; D020246:Venous Thrombosis / Q000209:etiology*; D055815:Young Adult
chemical_list: C095381:factor V Leiden; D005165:Factor V; D011516:Prothrombin; D004247:DNA; D042965:Methylenetetrahydrofolate Reductase (NADPH2)
keywords: 20209C>T mutation homozygosis; deep vein thrombosis; prothrombin; thrombosis