Factor XI deficiency is a disorder characterized by mild but potentially uncontrolled bleeding.
This bleeding becomes more severe after surgeries, injuries, or childbirth, especially after dental or urinary-tract procedures. Individuals with this condition may experience bruising, nosebleeds, or blood in urine, and male children might bleed heavily after circumcision. Women with factor XI deficiency often suffer from abnormally heavy and prolonged menstrual periods. Spontaneous bleeding without an obvious cause is uncommon, but there might be a delay in bleeding following an injury. The condition results from lower levels of the factor XI protein which aids in blood clotting and vessel healing after injury. While bleeding issues typically arise when factor XI levels drop below 15% of normal, problems can occur even at levels as high as 70%. The severity of bleeding varies widely among affected individuals, even within the same family. Factor XI deficiency is not known to affect lifespan. In individuals who do not realize they have the disease, life-threatening bleeding is possible following surgery or injury.
Factor XI deficiency is caused by pathogenic (disease-causing) variants in the F11 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 11 chance to be a carrier.
Carriers of factor XI deficiency are at elevated risk for bleeding problems. Studies have suggested that 20 to 50% of carriers of the disease show “excessive bleeding”, although the definition of this phrase varies. Rarely, carriers have shown major bleeding problems.
Other names for this condition are F11 deficiency, factor 11 deficiency, hemophilia C, plasma thromboplastin antecedent deficiency, and Rosenthal factor deficiency (or syndrome or disease).