Hemophilia B
Christmas disease; Factor IX hemophilia; Bleeding disorder - hemophilia BHemophilia B is a hereditary bleeding disorder caused by a lack of blood clotting factor IX. Without enough factor IX, the blood cannot clot properly to control bleeding.
Causes
When you bleed, a series of reactions take place in the body that helps blood clots form. This process is called the coagulation cascade. It involves as many as 20 different special proteins called coagulation, or clotting factors. You may have a higher chance of excess bleeding if one or more of these factors are missing or are not functioning like they should.
Factor IX (nine) is one such coagulation factor. Hemophilia B is the result of the body not making enough factor IX. Hemophilia B is caused by an inherited X-linked recessive trait, with the variant gene located on the X chromosome.
X-linked recessive
Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occur...
Read Article Now Book Mark ArticleFemales have two copies of the X chromosome. If the factor IX gene on one chromosome does not work, the gene on the other chromosome can do the job of making enough factor IX.
Males have only one X chromosome. If the factor IX gene is missing on a boy's X chromosome, he will have Hemophilia B. For this reason, most people with hemophilia B are male.
If a woman has a variant factor IX gene, she is considered a carrier. This means the variant gene can be passed down to her children. Boys born to such women have a 50% chance of having hemophilia B. Their daughters have a 50% chance of being a carrier.
All female children of men with hemophilia carry the variant gene whereas male children do not.
Risk factors for hemophilia B include:
- Family history of bleeding
- Being male
Symptoms
Severity of symptoms can vary. Prolonged bleeding is the main symptom. It is often first seen when the infant is circumcised. Other bleeding problems usually show up when the infant starts crawling and walking.
Bleeding
Bleeding is the loss of blood. Bleeding may be:Inside the body (internal)Outside the body (external)Bleeding may occur:Inside the body when blood le...
Read Article Now Book Mark ArticleMild cases may go unnoticed until later in life. Symptoms may first occur after surgery or injury. Internal bleeding may occur anywhere.
Symptoms may include:
- Bleeding into joints with associated pain and swelling
-
Blood in the urine or stool
Blood in the urine
Blood in your urine is called hematuria. The amount may be very small and only detected with urine tests or under a microscope. In other cases, the...
Read Article Now Book Mark Article -
Bruising
Bruising
Bleeding into the skin can occur from broken blood vessels that form tiny red dots (called petechiae). Blood also can collect under the tissue in la...
Read Article Now Book Mark Article - Gastrointestinal tract and urinary tract bleeding
-
Nosebleeds
Nosebleeds
A nosebleed is loss of blood from the tissue lining the nose. Bleeding most often occurs from one nostril only.
Read Article Now Book Mark Article - Prolonged bleeding from cuts, tooth extraction, and surgery
- Bleeding that starts without cause
Exams and Tests
If you are the first person in your family to have a suspected bleeding disorder, your health care provider will order a series of tests called a coagulation study. Once the specific variant has been identified, other people in your family will need tests to diagnose the disorder.
Tests to diagnose hemophilia B include:
-
Partial thromboplastin time (PTT)
Partial thromboplastin time
Partial thromboplastin time (PTT) is a blood test that looks at how long it takes for blood to clot. It can help tell if you have a bleeding problem...
Read Article Now Book Mark Article -
Prothrombin time (PT)
Prothrombin time
Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the functio...
Read Article Now Book Mark Article -
Serum factor IX activity
Serum factor IX
The factor IX assay is a blood test that measures the activity of factor IX. This is one of the proteins in the body that helps the blood clot....
Read Article Now Book Mark Article
Treatment
Treatment includes replacing the missing clotting factor. You will receive factor IX concentrates. How much you get depends on:
- Severity of bleeding
- Site of bleeding
- Your weight and height
To prevent a bleeding crisis, people with hemophilia and their families can be taught to give factor IX concentrates at home at the first signs of bleeding. People with severe forms of the disease may need regular, preventive infusions.
If you have severe hemophilia, you may also need to take factor IX concentrate before surgery or certain types of dental work.
You should get the hepatitis B vaccine. People with hemophilia are more likely to get hepatitis B because they may receive blood products.
Hepatitis B vaccine
All content below is taken in its entirety from the CDC Hepatitis B Vaccine Information Statement (VIS): www. cdc. gov/vaccines/hcp/vis/vis-statement...
Read Article Now Book Mark ArticleSome people with hemophilia B develop antibodies to factor IX. These antibodies are called inhibitors. The inhibitors attack factor IX so that it no longer works. In such cases, a man-made clotting factor called VIIa can be given.
Antibodies
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
Read Article Now Book Mark ArticleSupport Groups
You can ease the stress of illness by joining a hemophilia support group. Sharing with others who have common experiences and problems can help you not feel alone.
Hemophilia support group
The following organizations provide further information on hemophilia:Centers for Disease Control and Prevention -- www. cdc. gov/hemophilia/National...
Read Article Now Book Mark ArticleOutlook (Prognosis)
With treatment, most people with hemophilia B are able to lead a fairly normal life.
If you have hemophilia B, you should have regular checkups with a hematologist.
Possible Complications
Complications may include:
- Long-term joint problems, which may require a joint replacement
- Bleeding in the brain (intracerebral hemorrhage)
- Thrombosis due to treatment
When to Contact a Medical Professional
Contact your provider if:
- Symptoms of a bleeding disorder develop
- A family member has been diagnosed with hemophilia B
- If you have hemophilia B, and you plan to have children; genetic counseling is available
Prevention
Genetic counseling may be recommended. Testing can identify women and girls who carry the hemophilia gene.
Genetic counseling
Genetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...
Read Article Now Book Mark ArticleTesting can be done during pregnancy on a baby that is in the mother's womb.
References
Carcao M, Gomez K, Davide M, Pierce GF. Hemophilia A and B. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 134.
Ragni MV. Coagulation factor deficiencies. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 160.
Samelson-Jones BJ, Branchford BR, Flood VH. Hereditary clotting factor deficiencies (bleeding disorders). In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 525.
-
X-linked recessive genetic defects - how boys are affected - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. Since male offspring receive their X chromosome from their mothers, the inheritance of a defect attached to that one copy of the X will cause the disorder.
X-linked recessive genetic defects - how boys are affected
illustration
-
X-linked recessive genetic defects - how girls are affected - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. Females may get the defective gene either from her mother's defective X, or, if her father has the disorder, from her father. In either case, the girl will be a carrier and will probably pass the defect to her offspring. She will not manifest the disorder the way a boy would, because she has 2 X chromosomes, and the dominant X will compensate for the defect on the recessive X. Only if a female has 2 parents with the defect on their X chromosomes will she get a milder form of the disorder.
X-linked recessive genetic defects - how girls are affected
illustration
-
X-linked recessive genetic defects - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. If a woman has the defect on one of her X chromosomes, and the father's X chromosome is normal, there is a 25% chance for each pregnancy to produce an unaffected girl; a girl who carries the defect; an unaffected boy; or a boy with the disorder.
X-linked recessive genetic defects
illustration
-
Blood cells - illustration
Blood is comprised of red blood cells, platelets, and various white blood cells.
Blood cells
illustration
-
Blood clots - illustration
Blood clots (fibrin clots) are the clumps that result when blood coagulates.
Blood clots
illustration
-
X-linked recessive genetic defects - how boys are affected - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. Since male offspring receive their X chromosome from their mothers, the inheritance of a defect attached to that one copy of the X will cause the disorder.
X-linked recessive genetic defects - how boys are affected
illustration
-
X-linked recessive genetic defects - how girls are affected - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. Females may get the defective gene either from her mother's defective X, or, if her father has the disorder, from her father. In either case, the girl will be a carrier and will probably pass the defect to her offspring. She will not manifest the disorder the way a boy would, because she has 2 X chromosomes, and the dominant X will compensate for the defect on the recessive X. Only if a female has 2 parents with the defect on their X chromosomes will she get a milder form of the disorder.
X-linked recessive genetic defects - how girls are affected
illustration
-
X-linked recessive genetic defects - illustration
There are several X-linked (or sex-linked) recessive genetic disorders, (hemophilia, muscular dystrophy) which are inherited through a genetic defect on an X chromosome. A female has 2 X chromosomes, one she inherited from her mother and one she got from her father. A male has an X chromosome from his mother and a Y chromosome from his father. If a woman has the defect on one of her X chromosomes, and the father's X chromosome is normal, there is a 25% chance for each pregnancy to produce an unaffected girl; a girl who carries the defect; an unaffected boy; or a boy with the disorder.
X-linked recessive genetic defects
illustration
-
Blood cells - illustration
Blood is comprised of red blood cells, platelets, and various white blood cells.
Blood cells
illustration
-
Blood clots - illustration
Blood clots (fibrin clots) are the clumps that result when blood coagulates.
Blood clots
illustration
Review Date: 3/31/2024
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.