Hemophilia is an inherited blood disorder in which individuals are not born with a “clotting factor” that helps heal critical injuries. Hence, hemophilia patients bleed for a longer time externally and internally. There are two main types- hemophilia A and B. The third type, hemophilia C, is a rare condition. Each type is associated with a specific factor. This article focuses on the types and risk factors of hemophilia.
Types of hemophilia
Hemophilia A
Hemophilia A is linked to the deficiency or defective Factor VIII. It is typically passed down from parents to children, but one-third of cases had no prior family history. According to the US Centers for Disease Control and Prevention (CDC), this type occurs in 1 in about 5600 births. The X chromosome carries the genes for hemophilia. There are two X chromosomes inherited by females, one from their mother and one from the father (XX). Males inherit one X chromosome from their mother and one Y chromosome from their father (XY). This means that males getting hemophilia from their mothers is higher. Since females have two XX chromosomes, even if they carry the hemophilia gene from the mother, most likely, they will inherit healthy chromosomes from their father, thus making their chances significantly less. Hemophilia A has three stages depending on the ratio of Factor VIII. Mild hemophilia A has 6-30%, moderate has 1-5%, and severe has less than 1%.
Hemophilia B
Hemophilia B is linked to the deficiency or defective Factor IX. It is also called the Christmas disease and is four times less common than hemophilia A. Genetics of this type are the same as mentioned earlier. A female who inherits hemophilia chromosomes is called a carrier since she can pass it on to her children. The three severity stages are the same as hemophilia A. Symptoms of mild hemophilia B are typically known only after a serious injury, trauma, or tooth extraction. Women may experience menorrhagia or heavy menstrual bleeding. They may also undergo hemorrhage after childbirth. In moderate hemophilia B, bleeding may sometimes occur without any reason. In cases of severe hemophilia B, individuals may experience frequent spontaneous bleeding in joints and muscles. The severity of symptoms of hemophilia A and B are almost the same.
Hemophilia C
Hemophilia C is caused due to Factor XI deficiency. First recognized in 1953, approximately 1 in 100,000 people are affected by this type of hemophilia. The genetics of hemophilia C is different from the previous two types. This condition is inherited when both parents pass on the defective hemophilia gene to the child. This means both men and women are affected by it equally. Factor XI is an important clotting element since it creates a thrombin protein that gets converted to fibrin. It helps keep blood clots in place. People with hemophilia C may experience common joint and muscle bleeds, nosebleeds, or soft tissue bleeds.
Risk factors of hemophilia
Inherited genes
After an injury or surgery, the sealing of damaged blood vessels and preventing excessive blood loss are managed through blood clots. Both coagulation factors work together in the blood clotting process. Patients with hemophilia are born with mutations in their F8 and F9 genes, and hence an abnormal version of the coagulation factor VIII or XI lowers the quantity of these proteins. The changed or missing protein is incapable of forming blood clots, and as a result, the body cannot heal on its own in case of an injury. These missing coagulation factors sometimes lead to continuous bleeding, which is difficult to control or stop.
Mutations are the main risk factors for hemophilia. Men born into a family known to have a history of hemophilia are excessively at risk. The defect of hemophilia is found in the X chromosome, which mostly males inherit from their mothers. Women are at lower risk since they have two X chromosomes which come from both mother and father. However, in rare circumstances, the disease can also affect them.
Non-inherited genes
In rare circumstances, patients can develop acquired hemophilia (AH) whose risk factors are not associated with inherited genes. This auto-immune disease causes abnormal bleeding into the skin, muscles, or soft tissues and happens when specialized proteins, known as autoantibodies, attack and disable factor VIII coagulation. Autoantibodies are called inhibitors because they affect the function of the clotting factor. AH is extremely uncommon in children and usually affects aged people who have no earlier history of bleeding disorders. This disease is sometimes associated with pregnancy and immune system disorders. Other existing conditions that can lead to acquired hemophilia include lupus, rheumatoid arthritis, multiple sclerosis, Sjogren syndrome, and temporal arteritis. Inflammatory bowel disease or ulcerative colitis, diabetes, hepatitis, respiratory or dermatological diseases, Von Willebrand disease, and blood (hematological) cancer can also form acquired hemophilia later.
