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Hemophilia B

Christmas disease; Factor IX hemophilia; Bleeding disorder - hemophilia B

 

Hemophilia 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 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 1 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 defective gene located on the X chromosome.

Females have 2 copies of the X chromosome. If the factor IX gene on 1 chromosome does not work, the gene on the other chromosome can do the job of making enough factor IX.

Males have only 1 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 defective factor IX gene, she is considered a carrier. This means the defective 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 defective gene.

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 an infant is circumcised. Other bleeding problems usually show up when the infant starts crawling and walking.

Mild 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
  • Bruising
  • Gastrointestinal tract and urinary tract bleeding
  • Nosebleeds
  • Prolonged bleeding from cuts, tooth extraction, and surgery
  • Bleeding that starts without cause

 

Exams and Tests

 

If you are the first person in the family to have a suspected bleeding disorder, your health care provider will order a series of tests called a coagulation study. Once the specific defect 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)
  • Prothrombin time
  • Bleeding time
  • Fibrinogen level
  • Serum factor IX activity

 

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.

Some 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.

 

Support 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.

 

Outlook (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 check ups 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

 

Call 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.

Testing can be done during pregnancy on a baby that is in the mother's womb.

 

 

Open References

References

Carcao M, Moorehead P, Lillicrap D. Hemophilia A and B. In: Hoffman R, Benz EJ, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds. Hematology: Basic Principles and Practice . 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 137.

Scott JP, Flood VH. Hereditary clotting factor deficiencies (bleeding disorders). In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 476.

Srivastava A, Brewer AK, Mauser-Bunschoten EP, et al. Treatment Guidelines Working Group on Behalf of The World Federation Of Hemophilia. Haemophilia . 2013;19:e1-e47. PMID: 22776238 www.ncbi.nlm.nih.gov/pubmed/22776238 .

 
  • X-linked recessive genetic defects - how boys are affected

    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

    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

    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

    Blood cells - illustration

    Blood is comprised of red blood cells, platelets, and various white blood cells.

    Blood cells

    illustration

  • Blood clots

    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

      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

      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

      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

      Blood cells - illustration

      Blood is comprised of red blood cells, platelets, and various white blood cells.

      Blood cells

      illustration

    • Blood clots

      Blood clots - illustration

      Blood clots (fibrin clots) are the clumps that result when blood coagulates.

      Blood clots

      illustration

    Self Care

     

      Tests for Hemophilia B

       
         

        Review Date: 2/1/2016

        Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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