Storage Pool Disorders (Gray Platelet Syndrome)
Overview
Storage pool disorders are a group of inherited disorders caused by abnormalities with platelet granules. Granules are small packets inside the platelets in which proteins and other chemicals important to their function are stored. The contents of the granules are released during the secretion phase of platelet activation, acting as chemical signals to recruit more platelets and other cells to the site of injury to stop the bleeding. There are two types of granules: alpha granules and dense granules. Some storage pool deficiencies are caused by a lack of granules or their contents, but the most common ones are caused by a failure of the platelets to release their contents into the bloodstream.1
Types
- Release defects are a diverse group of disorders caused by an abnormality in the secretion mechanism. Even though the granules are present within the platelets, their contents are not emptied into the bloodstream properly.1
- Delta storage pool deficiency is a platelet function disorder caused by a lack of dense granules and the chemicals normally stored inside them. Without these chemicals, platelets are not activated properly and the injured blood vessel does not constrict to help stop bleeding. This type of bleeding problem can be seen in other inherited conditions such as Hermansky-Pudlak and Chediak-Higashi syndromes.1
- Grey platelet syndrome is a very rare platelet function disorder caused by a lack of alpha granules and the chemicals normally stored inside them. Without these chemicals, platelets cannot stick to the blood vessel wall, clump together, or repair the injured blood vessel the way they should.1
Symptoms
Symptoms of storage pool deficiencies vary from one individual to the next and are usually mild to moderate. People with storage pool deficiencies may experience:
- Easy bruising
- Nose bleeds (epistaxis)
- Bleeding from gums
- Heavy or prolonged menstrual bleeding (menorrhagia), bleeding during ovulation, or bleeding during or after childbirth
- Abnormal bleeding during or after surgery, circumcision, or dental work1
Causes
It is a disorder that is inherited or passed down from a child’s parent(s).