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Gray platelet syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Gray platelet syndrome

Gray platelet syndrome is a rare bleeding disorder characterized by abnormal platelets, leading to easy bruising, increased bleeding risk, and often associated with myelofibrosis and an enlarged spleen.

Overview

Gray platelet syndrome is a bleeding disorder associated with abnormal platelets, which are small blood cells involved in blood clotting. People with this condition tend to bruise easily and have an increased risk of nosebleeds (epistaxis). They may also experience abnormally heavy or extended bleeding following surgery, dental work, or minor trauma. Women with gray platelet syndrome often have irregular, heavy periods (menometrorrhagia). These bleeding problems are usually mild to moderate, but they have been life-threatening in a few affected individuals.

A condition called myelofibrosis, which is a buildup of scar tissue (fibrosis) in the bone marrow, is another common feature of gray platelet syndrome. Bone marrow is the spongy tissue in the center of long bones that produces most of the blood cells the body needs, including platelets. The scarring associated with myelofibrosis damages bone marrow, preventing it from making enough blood cells. Other organs, particularly the spleen, start producing more blood cells to compensate; this process often leads to an enlarged spleen (splenomegaly).

Frequency

Gray platelet syndrome appears to be a rare disorder. About 60 cases have been reported worldwide.

Causes

Gray platelet syndrome can be caused by mutations in the NBEAL2 gene. Little is known about the protein produced from this gene. It appears to play a role in the formation of alpha-granules, which are sacs inside platelets that contain growth factors and other proteins that are important for blood clotting. In response to an injury that causes bleeding, the proteins stored in alpha-granules help platelets stick to one another to form a plug that seals off damaged blood vessels and prevents further blood loss.

Mutations in the NBEAL2 gene disrupt the normal production of alpha-granules. Without alpha-granules, platelets are unusually large and fewer in number than usual (macrothrombocytopenia). The abnormal platelets also appear gray when viewed under a microscope, which gives this condition its name. A lack of alpha-granules impairs the normal activity of platelets during blood clotting, increasing the risk of abnormal bleeding. Myelofibrosis is thought to occur because the growth factors and other proteins that are normally packaged into alpha-granules leak out into the bone marrow. The proteins lead to fibrosis that affects the bone marrow's ability to make new blood cells.

Some people with gray platelet syndrome do not have an identified mutation in the NBEAL2 gene. In these individuals, the cause of the condition is unknown.

Associated Gene

  • NBEAL2

Inheritance

When gray platelet syndrome is caused by NBEAL2 gene mutations, it has an autosomal recessive pattern of inheritance, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene in each cell.

Gray platelet syndrome can also be inherited in an autosomal dominant pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder. An affected person often inherits the condition from one affected parent. Researchers are working to determine which gene or genes are associated with the autosomal dominant form of gray platelet syndrome.

Other Names for This Condition

  • BDPLT4
  • Bleeding disorder, platelet-type, 4
  • Deficient alpha granule syndrome
  • GPS
  • Grey platelet syndrome
  • Platelet alpha granule deficiency
  • Platelet alpha-granule deficiency
  • Platelet granule defect

Frequently Asked Questions

Myelofibrosis is a hallmark of gray platelet syndrome where scar tissue builds up in the bone marrow, reducing its ability to produce blood cells. This scarring often leads to an enlarged spleen (splenomegaly) as the spleen takes over some blood cell production. Long-term, this can result in cytopenias (low blood cell counts), causing fatigue from anemia or increased infection risk from low white blood cells. Regular hematology follow-ups are necessary to monitor spleen size and blood counts, as the progression of fibrosis varies among individuals.
There is currently no cure for gray platelet syndrome, and treatment is primarily supportive, focusing on managing bleeding episodes and monitoring for complications of myelofibrosis. In rare, severe cases where bone marrow failure becomes life-threatening, a hematopoietic stem cell transplant (bone marrow transplant) may be considered, although this is a high-risk procedure and not routinely performed. Most patients manage the condition with careful avoidance of trauma, use of antifibrinolytic agents during bleeding events, and regular monitoring by a hematologist.
Patients with gray platelet syndrome often experience easy bruising and frequent nosebleeds, which can be managed with simple measures like applying pressure, using nasal saline sprays, and avoiding aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) that impair clotting. For dental work or minor surgeries, patients should inform their providers about the condition so that hemostatic agents or antifibrinolytic medications can be used to control bleeding. Regular monitoring of blood counts is essential, as the associated bone marrow fibrosis can lead to anemia or low white blood cell counts over time.
Gray platelet syndrome is often misdiagnosed as other platelet disorders like Bernard-Soulier syndrome or immune thrombocytopenia. A key distinguishing feature is the presence of "gray" platelets on a peripheral blood smear, which appear pale because they lack alpha-granules. Additionally, platelet counts are usually normal or only mildly reduced, unlike in many other bleeding disorders. Genetic testing for mutations in the NBEAL2 gene provides a definitive diagnosis and differentiates it from other causes of bleeding and myelofibrosis.
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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