Hemophilia B is also known as Christmas disease. It’s a rare genetic blood clotting disorder that can be fatal without treatment.

A person is born with hemophilia B, but it may not be diagnosed until later in life. It’s estimated that two-thirds of cases are inherited, according to the National Hemophilia Foundation.

The other cases are caused by spontaneous gene mutations that occur for unknown reasons during fetal development. The disease occurs almost exclusively in people who are male.

Read on to learn what causes hemophilia B, its symptoms, and how it’s treated.

Hemophilia B is a type of hemophilia, with the other types being hemophilia A and hemophilia C.

It is also known as factor IX hemophilia and is a rare genetic disorder in which your blood does not clot properly.

The condition is also sometimes called Christmas disease after Stephen Christmas, who was the first person diagnosed with the condition in 1952.

If you have hemophilia B, your body produces little or no factor IX, a protein that helps the blood clot. This leads to prolonged or spontaneous bleeding. The less factor IX your body produces, the worse your symptoms are. Without treatment, hemophilia B can be fatal.

The gene responsible for hemophilia B is carried on the X chromosome.

Male children inherit one X and one Y chromosome, while female children inherit two X chromosomes. If a male child inherits a mutated gene on his X chromosome from his female parent, he will develop hemophilia B.

On the other hand, female children with one mutated gene are carriers and can pass the gene to their children. Male parents with the mutated gene will always pass it on to their female children but not their male children.

In rare cases, both parents may have the mutated gene, but this is uncommon.

With each pregnancy, female carriers have a:

  • 25% chance of having a son with hemophilia B
  • 25% chance of having a daughter who’s a carrier of the disease
  • 25% chance of having an unaffected son
  • 25% chance of having an unaffected daughter

[the terms “male” and “female”]

In this article, we use “male and female” to refer to someone’s sex as determined by their chromosomes and “men and women” when referring to their gender (unless quoting from sources using nonspecific language).

Sex is determined by chromosomes, and gender is a social construct that can vary between time periods and cultures. Both of these aspects are acknowledged to exist on a spectrum both historically and by modern scientific consensus.

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Severe cases of hemophilia B are usually diagnosed in babies younger than one year old. Mild cases may not be diagnosed until a child reaches their toddler years or sometimes even adulthood.

In all cases, diagnosis usually happens after abnormal bleeding from an injury or surgery.

Events that may lead your doctor to suspect hemophilia B include:

  • prolonged bleeding, which can occur during circumcision, after surgical procedures or tooth extractions, following vaccinations, or from cuts or other wounds
  • unexplained, excessive bruising, or prolonged nosebleeds
  • unexplained blood in urine or feces caused by internal bleeding in the gastrointestinal or urinary tract
  • internal bleeding that pools in the joints, which causes pain and swelling

Severe cases of hemophilia B may cause unexplained bleeding in the skull after childbirth and spontaneous bleeding.

If you or your child shows symptoms of hemophilia B, your doctor may order blood screenings and tests to confirm the diagnosis. These may include:

  • factor IX test: determines how much of the clotting factor is present in your blood
  • activated partial thromboplastin time test (APTT): detects how fast your blood clots
  • prothrombin time (PT) test: another test that detects how quickly your blood clots
  • fibrinogen test: determines your body’s ability to form a clot
  • complete blood count (CBC): checks the size, type, and amount of various components of the blood, including red and white blood cells

Genetic testing

If you’re female with a family history of hemophilia B, you can have genetic testing to see if you carry the faulty gene. Genetic testing is a very accurate way to detect the responsible gene.

There’s no cure for hemophilia B, but there are treatments for the condition. Regular treatment is essential for managing the symptoms of hemophilia B.

Factor IX injections

Hemophilia B can be treated with factor IX injections to prevent or stop bleeding. The factor IX can be derived from donated human blood or made in a laboratory.

Artificial factor IX is called recombinant factor IX and is recommended over blood-derived factor because it’s safer.

Blood-derived factor IX is rarely used in the United States.

Preventive treatment

If you have a severe form of hemophilia B, you may need preventive blood transfusions to avoid or reduce prolonged and heavy bleeding, which is known as prophylaxis. These are especially important in children. If you receive blood-derived factors or blood transfusions, you should be vaccinated for hepatitis B.

People with severe hemophilia B are at a slight risk of:

  • life threatening blood loss
  • bleeding in the brain
  • long-term joint problems from internal bleeding

Treatment for hemophilia B can sometimes lead to abnormal blood clots. To prevent complications, get regular checkups and blood tests, and avoid aspirin and other platelet-acting medications.

A small percentage of people with hemophilia B will develop antibodies (known as inhibitors) against factor IX replacement therapy.

These antibodies destroy the replacement factor in factor IX injections, causing this treatment to be ineffective. Your doctor can test for your risk of developing inhibitors and prescribe alternative treatments if necessary.

When you first receive a diagnosis of hemophilia B, you may feel confused and overwhelmed.

Your healthcare professional is there to answer any questions you may have that would help you cope as you learn to live with the condition and receive treatment. Some questions you can ask include:

  • Does hemophilia run in my family, and how can I find out?
  • How severe is my hemophilia?
  • What is my treatment going to look like?
  • How do I protect myself from excessive bleeding in my day-to-day life?
  • What additional lifestyle changes can I make that may help?
  • Can I continue taking any current prescription medications or over-the-counter medications as needed?

In people with mild-to-moderate hemophilia, regardless of type, the death rate is 19% higher than in healthy people.

That said, life expectancy is continuing to improve. With treatment, most people with hemophilia B are likely to lead normal lives.

It’s important to make sure you avoid situations in which excess bleeding could occur. You also can receive blood clotting therapy before any surgery or after any injury.

Learn more about the life expectancy of people with hemophilia.

How serious is hemophilia B?

Without management, hemophilia can be life threatening, especially due to accidents or injuries that could lead to excessive bleeding. Talk with your doctor about ways you can prevent bleeding, tips on how to manage your condition if an injury occurs, and other supportive resources.

Can hemophilia B be cured?

There is no cure for hemophilia B, but the condition can be managed with treatment.

Why is hemophilia B called royal disease?

In addition to Christmas disease, hemophilia B is sometimes called the royal disease because a number of European royals in history are known to have either carried the gene for the disease or had the condition. For example, Queen Victoria of England was believed to be a carrier. Alexei Nikolaevich, the son of Emperor Nicholas II and Empress Alexandra Feodorovna of Russia, had the disease.

Hemophilia B, also known as factor IX hemophilia, is one of three types of hemophilia. It’s a rare genetic disorder that causes problems with blood clotting. It was first identified in 1952 by Stephen Christmas, who was diagnosed with it.

The severity of symptoms varies depending on the amount of factor IX produced by the body, but without proper treatment, hemophilia B can be life threatening.

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