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ITGB3 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

ITGB3 gene

The ITGB3 gene provides instructions for creating the beta3 subunit of the integrin αIIbβ3 receptor, which is essential for platelet cohesion and blood clot formation.

Normal Function

The ITGB3 gene provides instructions for making the beta3 subunit of a receptor protein called integrin alphaIIb/beta3 (αIIbβ3), which is found on the surface of small cells called platelets. Platelets circulate in blood and are an essential component of blood clots. The beta3 subunit attaches (binds) to the alphaIIb subunit, which is produced from the ITGA2B gene, to form integrin αIIbβ3. It is estimated that 80,000 to 100,000 copies of integrin αIIbβ3 are present on the surface of each platelet.

During clot formation, integrin αIIbβ3 binds to a protein called fibrinogen. Attachment of integrin αIIbβ3 from adjacent platelets to the same fibrinogen protein helps platelets cluster together (platelet cohesion) to form a blood clot. Blood clots protect the body after injury by sealing off damaged blood vessels and preventing further blood loss. Integrin αIIbβ3 can also bind other proteins on platelets and in the blood as well as proteins within the intricate lattice that forms in the space between cells (extracellular matrix) to ensure proper clot formation and promote wound healing.

Health Conditions Related to Genetic Changes

Glanzmann thrombasthenia

At least 130 mutations in the ITGB3 gene have been found to cause Glanzmann thrombasthenia, which is a rare bleeding disorder. The mutations that cause this disorder occur in both copies of the gene in each cell and impair the production or activity of the beta3 subunit, which disrupts the formation of functional integrin αIIbβ3. A shortage (deficiency) of functional integrin αIIbβ3 prevents sufficient binding of fibrinogen or other proteins, impairing the formation of blood clots. A lack of platelet cohesion leads to prolonged or spontaneous bleeding episodes experienced by people with Glanzmann thrombasthenia.

Other disorders

Mutations in the ITGB3 gene can also cause another rare bleeding disorder called platelet-type bleeding disorder 16. People with this disorder have signs and symptoms similar to Glanzmann thrombasthenia, including frequent nosebleeds (epistaxis), bleeding from the gums, or red or purple spots on the skin caused by bleeding underneath the skin (petechiae), but the episodes are typically milder.

Unlike Glanzmann thrombasthenia, this disorder results from a mutation in only one copy of the ITGB3 gene in each cell, and the mutations result in the formation of some integrin αIIbβ3 that is abnormally turned on (active), even when no clot is being formed. This abnormally active protein is unable to reach the surface of the platelet where it is needed to bind to other platelets during clot formation. The overactive integrin αIIbβ3 binds inappropriately to clotting proteins within the cell during the formation of platelets, causing the platelets to become misshapen and large. The abnormally shaped platelets have a shortened lifespan, so platelet numbers are often reduced, which impairs clot formation. The combination of reduced numbers of enlarged platelets is referred to as macrothrombocytopenia.

Other Names for This Gene

  • beta 3 integrin
  • CD61
  • GP3A
  • GPIIIa
  • integrin beta 3
  • integrin beta-3 precursor
  • integrin, beta 3 (platelet glycoprotein IIIa, antigen CD61)
  • platelet glycoprotein IIIa
  • platelet GPIIIa
  • platelet membrane glycoprotein IIIa
  • vitronectin receptor beta chain

Frequently Asked Questions

Individuals with this condition often experience easy bruising, frequent nosebleeds, and heavy menstrual bleeding. More serious risks include bleeding from the gums, prolonged bleeding after dental procedures or surgery, and in rare cases, gastrointestinal bleeding. Patients must be cautious with activities that could cause trauma and must inform all healthcare providers about their condition before any medical or dental procedures.
Standard complete blood counts often show a normal platelet number, which can lead to misdiagnosis. Diagnosis requires specialized tests such as platelet aggregation studies, which measure how well platelets clump together in response to different chemicals. Genetic testing for mutations in the ITGB3 or ITGA2B genes can also confirm the diagnosis by identifying the specific genetic cause of the receptor defect.
The ITGB3 gene provides instructions for the beta-3 subunit of the alpha-IIb/beta-3 receptor, which is the primary "glue" that allows platelets to stick together. When this gene is mutated, the receptor is either not produced or does not function correctly. Without functional receptors, platelets cannot bind to fibrinogen to form a stable plug, resulting in prolonged bleeding from even minor cuts or injuries.
No, in fact, patients with Glanzmann thrombasthenia are generally advised to avoid aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) because these medications interfere with platelet function and can worsen bleeding. Treatment usually involves avoiding these drugs and using specific therapies like desmopressin or platelet transfusions for significant bleeding events.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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