Factor XI Deficiency
Factor XI deficiency, which is also known as hemophilia C, occurs when a person has a mutated F11 gene. This causes low levels or poor use of a blood protein factor — factor 11 — that helps blood clots to form. Men and women are equally likely to be carriers or to suffer from factor XI deficiency. Genetically, those of Ashkenazi Jewish descent are more often carriers. It’s the most common blood disorder overall and the second most common for women, according to the World Federation of Hemophilia.
Because their blood doesn’t clot correctly, the person with factor XI deficiency doesn’t heal the way they should. Their wounds may bleed longer or more heavily than normal. They’re also prone to nosebleeds and they bruise more easily than is typical. In addition, even simple surgeries — including dental work — are risky and require additional treatment with plasma transfusions to prevent complications and to aid healing.
About half of women with factor XI deficiency experience prolonged, heavy menses. It’s also common for these women to bleed heavily and for an extended period of time after giving birth. Postpartum hemorrhage often needs extra treatment in the form of frozen, fresh plasma transfusions. Cesarean deliveries require more extensive care.
It is difficult to establish exactly how widespread this disease is, since many people, especially men, present few symptoms and are thus less apt to consult a doctor to obtain a diagnosis. In the American population overall, one person in 100,000 is diagnosed with factor XI deficiency, regardless of degree of severity. The Ashkenazi Jewish population and a few other isolated groups are exceptions to the rule, since they show a much higher incidence—as high as 8% of the population, including both individuals with a single abnormal gene and those with two abnormal genes. This is the most common genetic disorder found in these populations. This is due to the higher probability that parents who are carriers of one or more defective genes, in a group isolated by
geographical, cultural, religious or other factors, will conceive children who are carriers of the same defective gene.
This issue is passed on to children autosomally — through non-sex chromosomes — and is recessive. This means that if one parent possesses a mutated allele (in other words, is a carrier), their children will be carriers as well. If both parents are carriers, each child has a 50 percent chance of being a carrier and a 25 percent chance of being born with a Factor XI deficiency.
From the Canadian Hemophilia Society “For reasons that are still unknown, the tendency to bleed is not always directly proportional to the level of blood factor XI. Two people with similar factor XI levels may present completely different symptoms. As a result, it is very difficult to predict the severity and frequency of bleeding simply on the basis of the percentage of factor XI in the blood. Personal and family history of bleeding, however, can predict a tendency to bleed, even though it may be variable over time in a single individual. A strong tendency to bleed may be due to the coexistence of two inherited disorders that affect blood coagulation in the same individual. For example, von Willebrand disease is a relatively frequent coagulation anomaly that affects up to 1% of the population, and the symptoms of this condition are similar to factor XI deficiency. Some very small groups, such as the Ashkenazi Jewish population, have inherited more serious forms of the disorder, which manifest as more acute, more frequent episodes of hemorrhaging. The serious forms are due either to a larger mutation or to the presence of two defective genes.
Prolonged bleeding may occur in particular after a major physical trauma, after an accident, or after surgery involving the buccal, nasal, genital or urinary mucosa. Tooth extraction, onsillectomy and ablation of the uterus or prostate are examples of surgeries that entail a high risk of bleeding. People with the disorder also have a strong tendency to develop nosebleeds and ecchymoses (bruises), and more rarely, bleeding into the urine or intestines. However, they do not have a tendency to bleed into muscles or joints; they therefore do not suffer the long-term effects associated with bleeding of this kind. Nor is there a high risk of suffering spontaneous intracranial bleeding, at least not without associated trauma.”
Taking a carrier DNA tests for Factor XI deficiency to screen for this disorder ensures that you’ll be ready when you have children. This is especially important with bleeding disorders since they can cause unpredictable complications. The cost for Factor XI deficiency testing varies, but it can run for as much as 1200 dollars, USD. It’s a small price to pay for peace of mind and preparedness.