Overview
Hemophilia is a rare condition in which the blood doesn't clot well. That's because it doesn't have enough blood-clotting proteins, called clotting factors. People with hemophilia might bleed longer after an injury than they would if the blood clotted as it should.
Small cuts aren't often much of a problem. For people with a serious form of hemophilia, the main concern is bleeding inside the body. Internal bleeding can damage organs and tissues and be life-threatening.
Gene changes that are passed through families, called inherited changes, are almost always the cause of hemophilia. Treatment includes regular replacement of the specific clotting factor that is low. There are newer therapies that don't have clotting factors, as well.
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Symptoms
Symptoms of hemophilia vary, depending on the level of clotting factors. People with a slightly low clotting-factor level might bleed only after surgery or injury. People with a low amount of clotting factor may bleed easily for what seems like no reason, called spontaneous bleeding.
People with serious hemophilia often have symptoms in the first two years of life. For instance, an infant with severe hemophilia may first bleed too much during a heel stick to draw blood for newborn screening tests. People with milder hemophilia might not know they have the condition until later in life, maybe after injury or surgery.
Symptoms of hemophilia include:
- A lot of bleeding from cuts or injuries, or after surgery or dental work.
- Many large or deep bruises.
- Bleeding more than is typical after vaccinations.
- Hot, swollen and painful joints. Bleeding is common in the knees, ankles and elbows.
- Blood in urine or stool.
- Nosebleeds with no known cause.
- In infants, being cranky for no known reason.
Bleeding into the brain
A simple bump on the head can cause bleeding into the brain for some people who have serious hemophilia. This is rare, but it's one of the most serious complications of the condition. Symptoms include:
- Having a painful, long-lasting headache.
- Repeated vomiting.
- Feeling sleepy or sluggish.
- Having convulsions or seizures.
When to see a doctor
Seek emergency care if you or your child has:
- Symptoms of bleeding into the brain.
- Bleeding that won't stop after an injury.
- Swollen joints that feel hot and are painful.
Causes
The cause of hemophilia is a missing or low level of a clotting factor. Clotting factors are proteins in the blood that work with cells called platelets to form clots. Most often, when people bleed, blood cells pool together to form a clot to stop the bleeding. A missing or low clotting factor keeps blood from clotting well in people with hemophilia.
Congenital hemophilia
Hemophilia is most often inherited, meaning a person is born with the condition. This is called congenital. Congenital hemophilia is classified by the type of clotting factor that's low.
The most common type of congenital hemophilia is hemophilia A, linked with a low level of factor 8. The next most common type is hemophilia B, linked with a low level of factor 9.
Acquired hemophilia
Some people get hemophilia with no family history of the condition. This is called acquired hemophilia.
Acquired hemophilia happens when a person's immune system attacks clotting factor 8 or 9 in the blood. It can be linked with:
- Pregnancy.
- Autoimmune conditions.
- Cancer.
- Multiple sclerosis.
- Drug reactions.
Hemophilia inheritance
In the most common types of hemophilia, the changed gene is on the X chromosome. Everyone has two sex chromosomes, one from each parent. People assigned female at birth get an X chromosome from the mother and an X chromosome from the father. People assigned male at birth get an X chromosome from the mother and a Y chromosome from the father.
This means that most people who get hemophilia are people assigned male at birth. The condition passes from mother to son through one of the mother's genes.
Most people assigned female at birth who have the changed gene are carriers. They tend to have no hemophilia symptoms. But some carriers can have bleeding symptoms if their clotting factors are lowered slightly.
Risk factors
The biggest risk factor for hemophilia is to have family members who also have the condition. People assigned male at birth are much more likely to have hemophilia than are people assigned female at birth.
Complications
Complications of hemophilia can include:
- Deep internal bleeding. Bleeding that happens in deep muscle can cause the arms and legs to swell. The swelling can press on nerves and lead to numbness or pain. Depending on where the bleeding happens, it may be life-threatening.
- Bleeding into the throat or neck. This can cause trouble with breathing.
- Damage to joints. Internal bleeding can put pressure on the joints, causing pain. Untreated, internal bleeding that happens often can cause arthritis or destroy the joint.
- Infection. If the clotting factors that treat hemophilia come from human blood, there's a risk of viral infections such as hepatitis C. Because of donor blood screening, the risk is low.
- Reaction to clotting factor treatment. In some people with hemophilia, the immune system reacts to the clotting factors that treat bleeding. When this happens, the immune system makes proteins that keep the clotting factors from working. This may keep treatment from working well.