Hemophilia is a rare, inherited blood disorder that causes your blood to clot less, which results in an increased risk of bleeding or bruising.
Hemophilia happens because your body does not make enough protein (clotting factors) to help your blood form clots. Clotting factors are proteins in your blood. They work with your platelets to form blood clots that control bleeding. Low clotting factor levels increase bleeding risk.
There are several types of hemophilia. Hemophilia may be severe, moderate or mild based on the amount of clotting factor in your blood.
Healthcare providers treat this condition by replacing the missing clotting factor. There is not a cure for hemophilia, but people who receive treatment generally live nearly as long as people who do not have hemophilia. Providers are researching gene therapy and gene replacement therapy as new ways to treat and possibly cure hemophilia.
Can people develop hemophilia?
Yes, but that rarely happens. Acquired hemophilia, or hemophilia that is not inherited, develops when autoantibodies start to attack a specific clotting factor. (Antibodies are protective proteins your immune system makes. Autoantibodies attack antibodies, essentially attacking your bodys own cells, tissues and proteins.)
Is hemophilia a common disease?
No, it is not. According to the U.S. Centers for Disease Control and Prevention (CDC) in August 2022, about 33,000 people in the U.S. have hemophilia. Hemophilia typically affects men and people assigned male at birth (AMAB). Rarely, women and people assigned female at birth (AFAB) may have clotting factor levels that are so low that they develop symptoms such as having very heavy periods.
What are hemophilia types?
There are three types of hemophilia:
- Hemophilia A: This is the most common type of hemophilia. It happens when you do not have enough clotting factor 8 (factor VIII). The CDC estimates about 10 in 100,000 people have hemophilia A.
- Hemophilia B: Hemophilia B happens when you do not have enough clotting factor 9 (factor IX.) The CDC estimates about 3 in 100,000 people in the U.S. have hemophilia B.
- Hemophilia C: Hemophilia C is also known as factor 11 (factor XI) deficiency. This hemophilia type is very rare, affecting 1 in 100,000 people.
- Is hemophilia a serious illness?
It can be. People with severe hemophilia may develop life-threatening bleeding, but they are more likely to develop bleeding in their muscles and joints.
SYMPTOMS AND CAUSES
What are hemophilia symptoms?
The most significant symptom is unusual or excessive bleeding or bruising.
- People with hemophilia may develop large bruises after minor injuries. This is a sign of bleeding under their skin.
- They may bleed for an unusually long time, whether that is bleeding after surgery, bleeding after dental treatment or simply bleeding from a cut finger.
- They may start bleeding for no apparent reason, such as sudden bloody noses.
- How much bruising or bleeding people have depends on whether they have severe, moderate or mild hemophilia:
People with severe hemophilia often have spontaneous bleeding or bleeding for no apparent reason.
People with moderate hemophilia who have serious injuries may bleed for an unusually long time.
People with mild hemophilia may have unusual bleeding, but only after major surgery or injury.
Other symptoms may include:
Joint pain from internal bleeding. Joints in your ankles, knees, hips and shoulders may ache, swell or feel hot to the touch.
Bleeding into your brain. People with severe hemophilia very rarely develop life-threatening bleeding into their brains. Brain bleeds may cause persistent headaches, double vision or make you feel very sleepy. If you have hemophilia and have these symptoms, get help right away.
What are hemophilia symptoms in babies and children?
Sometimes, babies assigned male at birth with hemophilia are diagnosed because they bleed more than usual after being circumcised. Other times, children develop symptoms a few months after they are born. Common symptoms include:
Bleeding: Babies and toddlers may bleed from their mouths after minor injuries, like bumping their mouths on a toy.
Swollen lumps on their heads: Babies and toddlers who bump their heads often develop goose eggs — large round lumps on their heads.
Fussiness, irritability or refusal to crawl or walk: These symptoms may happen if babies and toddlers have internal bleeding into a muscle or joint. They may have areas on their bodies that look bruised and swollen, feel warm to your touch or make your child hurt when you gently touch the area.
Hematomas: A hematoma is a mass of congealed blood that gathers under babies or toddlers skin. Babies and toddlers may develop hematomas after receiving an injection.
What causes hemophilia?
Certain genes create clotting factors. In inherited hemophilia, the genes carrying instructions for making normal clotting factors mutate or change. The mutated genes may give instructions that end up making abnormal clotting factors or not enough clotting factors. That said, about 20% of all hemophilia cases are spontaneous, meaning someone has the disease even though there is no family history of abnormal bleeding.
How do people inherit hemophilia?
Hemophilia A and B are both sex-linked disorders that are inherited in an X-linked recessive manner. Here is how that happens:
- Everyone receives one set of chromosomes from their biological mother and one set of chromosomes from their biological father. If you get an X chromosome from your mother and an X chromosome from your father, you are assigned female at birth. If you get an X chromosome from your mother and a Y chromosome from your father, you are assigned male at birth. In other words, a mother will always pass an X chromosome to her offspring. The father will determine the assigned sex at birth by providing either an X or a Y chromosome.
- If a woman has an abnormal factor gene on one of their X chromosomes, they carry hemophilia but may not have symptoms. That is because there is a normal factor gene on their second X chromosome.
- If a woman who carries an X chromosome with a defective gene for producing factor 8 (or factor 9) has a male child, that child has a 50% chance of inheriting the X chromosome that carries the abnormal factor gene.
- If that same woman has a female child, that child has a 50% chance of inheriting the faulty chromosome and abnormal factor gene. That child likely would not have symptoms because they will also inherit a normal X chromosome from their father.
- In other words, a woman who inherits a faulty X chromosome and abnormal factor gene will carry hemophilia. They may not have symptoms, but they can pass the condition on to their children. There is a 50% chance that any children they have — boys or girls — will inherit hemophilia. Boys who do inherit hemophilia are more likely to have severe symptoms. That is because they do not get a healthy X chromosome from their father.
Do women ever develop hemophilia symptoms?
They can, but those symptoms tend to be mild. For example, a woman carrying the hemophilia gene may not have the normal clotting factors or not enough clotting factors. When that happens, they may have unusually heavy menstrual periods and they may bruise easily. They may bleed more after childbirth and they may develop joint problems if they have internal bleeding into their joints.
