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GP1BB gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GP1BB gene

The GP1BB gene provides instructions for making a protein essential for blood clotting and is associated with Bernard-Soulier syndrome.

Normal Function

The GP1BB gene provides instructions for making a protein called glycoprotein 1b-beta (GPIbβ). This protein is one subunit of a protein complex called GPIb-IX-V, which plays a role in blood clotting. This complex is found on the surface of platelets, small cells that circulate in the blood and are essential for forming blood clots.

The complex acts like a lock and key, binding to a protein called von Willebrand factor, which is found on the inner surface of blood vessels, particularly at sites of injury. This binding allows platelets to stick to the blood vessel wall, forming clots that plug holes in vessels to stop bleeding. To form the GPIb-IX-V complex, GPIbβ interacts with other subunits called GPIb-alpha, GPIX, and GPV. GPIbβ is essential for the assembly of this complex at the platelet surface and helps stabilize it once formed.

Health Conditions Related to Genetic Changes

Bernard-Soulier syndrome

At least 32 GP1BB gene mutations have been found to cause Bernard-Soulier syndrome, a condition characterized by excessive bleeding and a reduced number of platelets that are larger than normal (macrothrombocytopenia). These mutations lead to the production of an altered GPIbβ subunit that is either broken down too soon or cannot reach the platelet surface. The lack of this subunit prevents the formation of the GPIb-IX-V complex, meaning platelets cannot aggregate at injury sites to form clots.

Other Names for This Gene

  • antigen CD42b-beta
  • BDPLT1
  • BS
  • CD42C
  • glycoprotein Ib (platelet), beta polypeptide
  • glycoprotein Ib platelet beta subunit
  • GP-Ib beta
  • GPIBB
  • GPIbbeta
  • nuclear localization signal deleted in velocardiofacial syndrome
  • platelet glycoprotein Ib beta chain precursor
  • platelet membrane glycoprotein Ib beta
  • truncated platelet membrane glycoprotein Ib beta

Frequently Asked Questions

The absence of functional GPIb-beta leads to chronic bleeding risks, but with proper management, many individuals with Bernard-Soulier syndrome can lead normal lives with a near-normal life expectancy. The primary long-term health concerns are related to cumulative blood loss, which can lead to iron deficiency anemia, and the potential for severe hemorrhagic events during trauma or surgery. Regular monitoring of iron levels and proactive management of bleeding episodes are key to maintaining long-term health. There is no evidence that the genetic defect itself causes organ damage or shortens life in the absence of uncontrolled bleeding.
While both conditions involve the von Willebrand factor pathway, Bernard-Soulier syndrome (BSS) is a platelet disorder where the platelets themselves lack the receptor (GPIb-IX-V) needed to bind to von Willebrand factor. This results in macrothrombocytopenia, meaning patients have fewer but larger platelets. Bleeding in BSS is often more severe and prolonged compared to mild von Willebrand disease, frequently manifesting as significant mucosal bleeding, such as nosebleeds, gum bleeding, or heavy menstrual periods, and can be life-threatening during surgery or trauma.
Patients with BSS require careful hemostatic planning before any surgical procedure, including dental extractions. Standard platelet transfusions may be less effective because the transfused platelets can be rapidly destroyed by antibodies against the missing GPIb-IX-V complex. Therefore, clinicians often rely on antifibrinolytic agents like tranexamic acid or desmopressin (DDAVP) to stabilize clots. In major surgeries, platelet transfusions may still be necessary but must be administered with close monitoring for immune reactions, and the patient's specific antibody profile should be known in advance.
GP1BB mutations can be detected in newborns through a complete blood count (CBC), which will reveal thrombocytopenia (low platelet count) and significantly increased mean platelet volume (MPV). Early symptoms in infants may include easy bruising, petechiae (small red or purple spots on the skin), or prolonged bleeding from the umbilical cord stump. However, some infants may be asymptomatic until they experience a minor injury or undergo a procedure that triggers noticeable bleeding, making routine newborn screening or family history assessment crucial for early diagnosis.
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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