Platelet storage pool deficiencies
are rare platelet abnormalities that cause a mild to moderate bleeding disorder. Platelet storage pool deficiencies consist of a number of disorders characterized by a reduction in the number and content of certain types of platelets, called dense granules and alpha granules. The dense granules in platelets serve as a "storage pool" for adenosine triphosphate (ATP), adenosine diphosphate (ADP), serotonin, calcium, and pyrophosphate, which are secreted when platelets are activated. It is thought that the reduced release of ADP may result in the prolonged bleeding times.
Classically, the clinical features of storage pool disorders include nosebleeds (epistaxis), abnormally heavy or prolonged menstruation (menorrhagia), easy bruising, recurrent anemia, and obstetric or surgical bleeding. Four major types of congenital platelet storage pool disease have been described: dense body deficiency, gray platelet syndrome, Factor V Quebec, and mixed alpha-granule/dense body deficiency. The inheritance of an isolated platelet storage pool deficiency is thought to be autosomal dominant, but the penetrance of the gene varies from person to person.
Platelet storage pool deficiencies can also be part of other inherited conditions including Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and thrombocytopenia-absent radius (TAR) syndrome which are autosomal recessive conditions, and Wiskott-Aldrich syndrome, an X-linked recessive condition. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.