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Platelet Disorders

What is a Platelet Disorder?

A platelet disorder is a group of conditions that are caused by a problem with the platelets. Platelet disorders can either be:

  • Acquired – they develop during your lifetime
  • Inherited – you are born with the condition

What are Platelets and What Do They Do?

Platelets are the smallest of our blood cells, but they have a very big job to do when there is bleeding. When you cut or injure a blood vessel,

  • Platelets rush to the site of the injury.
  • Platelets stick to each other and to the area of the blood vessel that is bleeding.
  • As more and more platelets gather, they signal for other helpers like clotting factors to come to the site and help stop the bleeding.

When everything works right, a platelet plug is formed that helps stop the bleeding.

Why Don’t Platelets Work Right if You Have a Platelet Disorder?

There are several reasons why platelets might not work right.

  • There may be a problem on the surface of the platelets that prevent them from sticking together.
  • There may be a problem with parts inside the platelets called granules.
  • There may not be enough platelets.
  • There may be a problem with the size of the platelets – they may be too big or too small.
  • There may be a problem with how platelets signal for more platelets or other helpers like clotting factors.

Types of Platelet Disorders

Acquired Platelet Disorders

Immune Thrombocytopenia (ITP)

ITP is not an inherited disorder. It develops during a person’s lifetime and is actually an autoimmune disorder that destroys platelets.

  • The immune system sees platelets as something that doesn’t belong in the body and the platelets are destroyed which causes a low level of platelets in the blood.
  • ITP often develops after a viral infection. As the body makes antibodies to fight off the virus, it may accidentally make antibodies that attack platelets.
  • When there aren’t enough platelets to help stop bleeding, a platelet plug cannot form.

Resource:
Platelet Disorder Support Association 

Inherited Platelet Disorders

Bernard-Soulier Syndrome (BSS)

Bernard-Soulier Syndrome (BSS) is a very rare, inherited platelet disorder that affects approximately 1 in 1 million people. It is also called Giant Platelet Syndrome because the platelets are very big.

  • BSS affects both males and females.
  • In BSS, platelets do not have a way to connect with the von Willebrand factor which is the “glue” that holds the platelets together.
  • When platelets can’t stick together, a platelet plug cannot form.

Resource:
NORD – Bernard-Soulier Syndrome (BSS)

Glanzmann Thrombasthenia (GT)

Glanzmann Thrombasthenia (GT)  is a very rare inherited platelet disorder. Only about 500 cases have ever been reported.

  • GT affects both males and females.
  • In GT, platelets that are in the immediate area of an injury stick together like they should, but they are missing a special protein that attracts more platelets to the site of an injury.
  • When there aren’t enough platelets, the platelet plug is very small and does not stop bleeding.

Resource:
NORD – Glanzmann-Thrombasthenia

Storage Pool Defects (SPD)

Storage Pool Defects (SPD) are a group of conditions caused by a problem with parts inside the platelets called granules. SPD can be inherited, or it can develop during a person’s lifetime. Platelet granules contain important ingredients to help stop bleeding. In normal clotting, the ingredients inside the granules are pushed out into the bloodstream to invite other platelets to come to the site of injury and stick together, forming a platelet plug. In SPD:

  • The granules inside the platelet may not be packaged correctly.
  • The granules may not be pushed out into the bloodstream.
  • There may not be enough or any granules inside the platelets.
  • Without properly functioning granules, a platelet plug cannot form.

Resource:
Hemophilia of Georgia Storage Pool Disease

Wiscott-Aldrich Syndrome (WAS)

Wiscott-Aldrich Syndrome (WAS) is an inherited immunodeficiency. It affects approximately 4 in 1 million live male births in the United States.

  • WAS occurs almost always in males.
  • The platelets are very small and the number of platelets in the blood is low, causing bleeding.

Resource:
Wiskott-Aldrich Foundation

Gray Platelet Syndrome (GPS)

Gray Platelet Syndrome (GPS) affects both males and females. Approximately 60 cases have been identified worldwide. It is called Gray Platelet Syndrome because, under the microscope, platelets have a gray color.

  • The gray color is a result of missing granules inside the platelet called alpha granules.
  • Without alpha granules, platelets cannot stick together.
  • In GPS, the platelet count is very low and the platelets are much larger than normal.

Resources: ASH PublicationsPlatelet Society

Quebec Platelet Disorder (QPD)

Quebec Platelet Disorder (QPD) is an inherited platelet disorder.

  • In QPD the platelet count is low.
  • In QPD, a clot is formed, but it breaks down too fast. After surgery, dental extractions, or trauma, there is not bleeding right away. But because the clot breaks down too fast, bleeding begins later.

Resources: PubMedQuebec Platelet Disorder, Journal of Thrombosis and Haemostasis

Hermansky-Pudlak Syndrome (HPS)

Hermansky-Pudlak Syndrome (HPS) is an inherited disorder. It is characterized by Oculocutaneous albinism, which is a generalized decreased pigmentation of hair, skin, and eyes. It is also characterized by prolonged bleeding.

  • In HPS, the platelets are missing dense granules resulting in platelets that don’t work correctly.
  • In HPS, the platelet count is typically normal.

Resources: New England Journal of Medicine articlePigment Cell ResearchOrphanet Journal of Rare Diseases

Chediak-Higashi Syndrome (CHS)

Chediak-Higashi Syndrome (CHS) is a complex, inherited disorder. It affects both males and females and there are less than 500 cases documented worldwide. CHS is characterized by:

  • Partial oculocutaneous albinism – decreased pigmentation of hair, skin, and eyes.
  • Immunodeficiency – the body’s immune system does not work properly to fight off infections.
  • Tendency to bruise or bleed easily.
  • The platelet count is typically normal, but the platelets do not work correctly.

Resources: NORD – Chediak Higashi SyndromeOrphanet Journal of Rare DiseasesNCBI Bookshelf, Mayo Clinic – Symptoms and Causes

Release Defects

Release Defects represent the largest group of platelet function disorders.

  • The granules inside the platelet are normal but the platelets are unable to push them into the bloodstream.