Hemophilia B is a rare inherited bleeding disorder. It happens when a gene that helps blood clot mutates or changes. Left untreated, hemophilia B may be life-threatening. Scientists are researching gene therapy and gene replacement therapy as new ways to treat hemophilia B and other forms of hemophilia.
Hemophilia B, once known as Christmas disease, is an inherited bleeding disorder. It happens when a gene that helps blood clot mutates or changes. People with hemophilia B don’t have the usual amount of a blood protein that helps blood clot. This protein is a clotting factor. In hemophilia B, people have less clotting factor IX, sometimes called factor 9, F9 or FIX. Left untreated, hemophilia B may be life-threatening. Healthcare providers treat hemophilia B with factor 9 replacements that help blood clot. Providers are researching gene therapy and gene replacement therapy as new ways to treat hemophilia B and other forms of hemophilia.
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Like other forms of hemophilia, people who have hemophilia B bleed more than normal and/or longer than normal after being injured, having surgery or having dental procedures. Hemophilia B mostly affects men and people designated male at birth (DMAB) but women and people designated female at birth (DFAB) may develop the condition, too.
Healthcare providers classify hemophilia as being mild, moderate or severe. People who have severe hemophilia B may have bleeding into their joints that’s very painful and may cause arthritis. Some people may need surgery to replace damaged joints. They also may have bleeding inside of their brain that can be life-threatening.
Experts estimate about 4 in 100,000 men and people DMAB in the United States have hemophilia B. Women and people DFAB can have hemophilia B, but it’s hard to estimate how many have this condition. That’s because they may have symptoms like heavy periods or excessive postpartum bleeding that many people don’t associate with hemophilia.
Both hemophilia types are inherited blood disorders with similar symptoms caused by different genetic mutations or changes. Studies show hemophilia B symptoms may be less serious than hemophilia A symptoms. Hemophilia B is still a serious medical condition, but people who have this form of hemophilia may have fewer issues with excessive bleeding. Some other differences between hemophilia A and B include:
For more than 100 years, healthcare providers thought there was just one type of hemophilia. In 1952, a researcher used plasma from seven people who had hemophilia — one with the last name Christmas — to treat other people who had hemophilia. The treatment worked. Researchers concluded Christmas’ hemophilia was a different form of hemophilia caused by a different genetic mutation. They named this second hemophilia type Christmas factor or Christmas disease. Later, Christmas disease was renamed hemophilia B.
Hemophilia B is a genetic bleeding disorder. If you have hemophilia B, it means you inherited an abnormal gene that affects the amount of clotting factor 9 in your body. Normally, a gene called F9 carries instructions on how to create factor 9. Hemophilia B happens when that gene mutates and becomes an abnormal gene that leads to low factor 9 levels or even missing factor 9. Men or people DMAB inherit hemophilia B if their biological mothers carry the condition.
Here’s how that happens:
Hemophilia B may happen without passing from mother to son through a process called spontaneous mutation. In spontaneous mutation, the embryo created when an egg and sperm combine starts to divide and produce more cells. The new cells contain copies of the genes in the single cell, and sometimes, mistakes or mutations happen during the gene copying process.
If there was a mistake when the F9 gene was copied, your child may have hemophilia B or carry hemophilia B. (Historians and medical researchers believe that was the case with Queen Victoria of England. Queen Victoria had hemophilia even though no one in her family had the disease. She passed the disease on to her children. When those children married into royal families in Spain and Russia, they passed the condition on to their children. That condition was later identified as hemophilia B.)
Hemophilia B symptoms are classified as mild, moderate or severe. Healthcare providers classify hemophilia symptoms by the level of factor 9 in people’s blood.
People who have factor 9 levels between 6% to 49% have mild hemophilia B and mild symptoms. In some cases, people with mild hemophilia B aren’t diagnosed until they’re adults and need surgery, give birth, have a serious injury or if they’re female, seek treatment to ease very heavy periods.
People who have factor 9 levels between 1% to 5% have moderate hemophilia B and moderate symptoms. Children with moderate hemophilia B typically start showing symptoms when they’re 18 months old.
These children may have the following symptoms:
People with factor 9 levels below 1% have severe hemophilia B and severe symptoms. Some children who have severe hemophilia B bleed as they’re being born, right after they’re born or when they’re undergoing circumcision. Other children develop symptoms a few months after they’re born. Common symptoms include:
Healthcare providers diagnose hemophilia B by doing a physical examination, evaluating symptoms, like bruising and swollen joints, and asking about any biological family history of hemophilia or blood disorders.
Healthcare providers typically treat hemophilia B with factor replacement therapy. In factor replacement therapy, providers inject concentrated factor 9 into people’s bloodstreams. The concentrated factor 9 takes the place of the missing factor and helps prevent excessive bleeding or control bleeding when it happens.
Usually, people with mild or moderate hemophilia B only need replacement therapy when they need surgery. People who have severe hemophilia B may need regular factor replacement therapy.
People receiving replacement therapy may develop complications, including inhibitors and viral infections.
People develop inhibitors when their bodies stop accepting factor replacement therapy as part of their normal blood. Inhibitors prevent factor replacement therapy from working, which makes it difficult to slow or stop bleeding episodes. People are more likely to develop this complication if they have severe bleeding disorders and are receiving high doses of factor replacement. Healthcare providers may treat this complication by using agents that can bypass factor 9 to complete clot formation.
Rarely, people may develop viral infections, particularly hepatitis C, if their treatment involves replacement therapy using donated blood.
Hemophilia B is an inherited condition, which means you can’t reduce your risk of developing it or passing it on to your children. Here’s information about the genetic process that drives hemophilia B:
Yes, healthcare providers can take a sample of blood from your umbilical cord to test clotting factors. That way, you and they will know what to expect during delivery and take steps to prevent any complications bleeding may cause.
Hemophilia B is a chronic condition. Healthcare providers can’t cure it, but they do have treatments that prevent or ease serious joint pain and other medical issues. Most people receiving treatment for hemophilia B have a good prognosis or expected outcome.
People who have severe hemophilia B will need regular infusions or injections of replacement factor for bleeding issues. They may need to see their healthcare provider for treatment, ask a family member or caregiver to inject the treatment or they may be able to inject the treatment themselves. Regardless, people with severe hemophilia B will always need treatment to prevent excessive bleeding.
They may also develop other medical conditions that affect their overall health and lifespan. For example, many people who have hemophilia B develop severe problems with their knee or hip joints and need surgery to replace the damaged joints. If you have hemophilia B, ask your healthcare provider what you may expect. They know your situation, including your overall health, and are the best resource for information.
If your child has mild or moderate hemophilia B, you’ll need to make sure healthcare providers know about the condition so they can prevent excessive bleeding if your child needs surgery or dental treatment like having a tooth pulled. Here are some other suggestions. Your healthcare provider may have more:
Children who have severe hemophilia B will need medical treatment for the rest of their lives, whether it’s treatment to prevent or slow bleeding or treatment to ease symptoms. Here are some potential challenges you may encounter, and some suggestions that may help:
Living with hemophilia B means being vigilant about receiving treatment and taking extra steps to protect your overall health. Here are some suggestions:
You should see your healthcare provider for your regular treatment and any time you have unusual bleeding or other symptoms like severe joint pain.
You should seek immediate medical help if you have a head injury. The following symptoms could mean you have brain bleed or hemorrhage (intracranial hemorrhage):
Contact your healthcare provider or go to the emergency room any time you can’t stop bleeding from any kind of injury or if you start to bleed for no apparent reason.
A note from Cleveland Clinic
Hemophilia B is a rare form of a rare disease. Like the more common form, hemophilia A, hemophilia B is an inherited bleeding d disorder. Studies show people with hemophilia B may have less serious symptoms than people who have hemophilia A. Even so, hemophilia B still poses medical, lifestyle and emotional challenges. Women and people designated female at birth (DFAB) who carry the condition may wonder and worry if they’ll pass it on to their children. Parents raising a child who has hemophilia B may feel anxious about protecting their children from accidental injury. Later, they may need to help their growing child learn to live with hemophilia B. People who have severe hemophilia B may need lifelong treatment to prevent excessive bleeding. Researchers are investigating new treatments like gene replacement or gene therapy that may make a huge difference in how healthcare providers treat severe hemophilia B. If you or your child have this condition, ask your healthcare provider for information about clinical trials that may be appropriate.
Last reviewed by a Cleveland Clinic medical professional on 07/22/2022.
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