Glanzmann thrombasthenia

What is Glanzmann thrombasthenia?
Glanzmann thrombasthenia is a platelet function disorder that is caused by an abnormality in the genes for glycoproteins IIb/IIIa. These genes code for a group of linked proteins  normally found on the surface of platelets, the glycoprotein IIb/IIIa receptor (also called the fibrinogen receptor). Because this receptor is absent or is not working properly, platelets do not stick to each other at the site of injury and it is difficult for the normal blood clot to form.

Glanzmann thrombasthenia is an autosomal recessive disorder, meaning that both parents must carry an abnormal gene (even though they themselves don’t have the disease) and pass that abnormal gene on to their child. Like all autosomal recessive disorders, it is found more frequently in areas of the world where marriage between close relatives is common. Glanzmann thrombasthenia affects both males and females.

Symptoms
Symptoms of Glanzmann thrombasthenia vary quite a bit from one individual to the next, from very mild to potentially life-threatening bleeding. Signs of the disorder are usually first noticed during childhood.

People with Glanzmann thrombasthenia may experience:

  • Easy bruising
  • Nose bleeds
  • Bleeding from gums
  • Heavy or prolonged menstrual bleeding (menorrhagia) or bleeding after childbirth
  • Abnormal bleeding after surgery, circumcision, or dental work
  • Rarely, vomiting blood or passing blood in urine or stool due to bleeding in the gut (gastrointestinal hemorrhage) or genito-urinary tract (kidneys, ureters, bladder, and urethra)

Glanzmann thrombasthenia often causes more problems for women than men because of menstruation and childbirth.

Diagnosis
The diagnosis of platelet function disorders requires a careful medical history and a series of tests that should be performed by a specialist at a hemophilia treatment centre.

In people with Glanzmann thrombasthenia:

  • The bleeding time (a standardized test of the time it takes for a small cut to stop bleeding) is longer than normal. This test may be difficult to perform in young children
  • The closure time (a test that measures the time it takes for a platelet plug to form in a sample of blood) is longer than normal
  • Platelets do not clump together the way they should with several different chemicals in a laboratory test (platelet aggregation).
  • GP IIb/IIIa is not detectable in blood samples (using a test called flow cytometry)

Note: Some of these tests may not be available in all centres.

Treatment
Most people with platelet function disorders only need treatment during surgical procedures (including dental work) and after injury or accidents. When needed, Glanzmann thrombasthenia may be treated with:

  • Antifibrinolytic drugs
  • Recombinant factor VIIa
  • Fibrin sealants
  • Hormonal contraceptives (to control excessive menstrual bleeding)
  • Iron replacement (if necessary to treat anemia caused by excessive or prolonged bleeding)
  • Platelet transfusions (only if bleeding is severe)

People with inherited platelet function disorders should not take Aspirin®, nonsteroidal anti-inflammatory drugs (such as ibuprofen and naproxen), and blood thinners, which can make their bleeding symptoms worse.

 

Updated May 2012

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