title: [Hemophilia C, a deficiency of a contact phase protein which may involve a risk of hemorrhage].
abstract: Factor XI deficiency, also called hemophilia C, was first described in 1953. It is thought to constitute 7% of all disorders of the intrinsic pathway of blood coagulation. It represents the only deficiency of a contact phase protein associated with a bleeding tendency with widely variable expression. Eighteen members of 5 families with this deficiency have been investigated; only 3 exhibited a hemorrhagic diathesis: 2/4 homozygous (hemorrhages after surgical procedures and hematomas and after minor traumatism) and 1/10 heterozygous individuals (hematomas, epistaxis). All homozygotes had a prolongation of the PTT. The hemorrhagic tendency was higher among homozygous individuals (with very low factor XI activity), but 2 were asymptomatic. Heterozygotes may also bleed. This deficiency is found mainly in an Ashkenazy Jewish population. Our study shows that it occurs in an apparently autochthonous Swiss population. A detailed history and studies of other family members are necessary if there is suspicion of factor XI deficiency.
authors.affiliation: Département de médecine interne, Centre hospitalier universitaire vaudois, Lausanne.
authors.forename: C
authors.initials: C
authors.lastname: Francillon
authors.forename: H
authors.initials: H
authors.lastname: Knecht
authors.forename: L
authors.initials: L
authors.lastname: Winkel
authors.forename: J
authors.initials: J
authors.lastname: Hauert
authors.forename: F
authors.initials: F
authors.lastname: Bachmann
mesh_terms: D000328:Adult; D000368:Aged; D001777:Blood Coagulation / Q000235:genetics; D002675:Child, Preschool; D005173:Factor XI Deficiency / Q000150:complications / Q000235:genetics*; D005260:Female; D006474:Hemorrhagic Disorders / Q000150:complications / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time
vernacular_title: Hémophilie C, un déficit de la phase de contact qui peut entraîner un risque hémorragique.