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Electron microscopic and functional studies on platelets in gray platelet syndrome
Insights
Gray platelet syndrome, a hereditary bleeding disorder, is characterized by platelet alpha-granule deficiency. This study investigated its ultrastructure and autosomal dominant inheritance pattern in 8 patients.
Area of Science:
- Hematology
- Genetics
- Cell Biology
Background:
- Gray platelet syndrome (GPS) is a rare inherited bleeding disorder.
- It is characterized by a deficiency of alpha-granules in platelets and their precursors, megakaryocytes.
- The clinical manifestations include prolonged bleeding time and impaired platelet aggregation.
Purpose of the Study:
- To investigate the ultrastructure and function of platelets and megakaryocytes in patients with GPS.
- To determine the mode of inheritance of GPS in an affected family.
- To identify morphological abnormalities associated with alpha-granule deficiency.
Main Methods:
- Hemostatic examinations (bleeding time, platelet retention, and aggregation studies).
- Analysis of ATP and ADP release.
- May-Giemsa staining of peripheral blood and bone marrow smears.
- Electron microscopy of platelets and megakaryocytes.
Main Results:
- Patients exhibited prolonged bleeding time, reduced platelet retention and aggregation, and diminished ATP/ADP release.
- Platelets and megakaryocytes showed a characteristic gray color due to alpha-granule deficiency.
- Electron microscopy revealed enlarged platelets with fewer alpha-granules, normal dense bodies and mitochondria, and various morphological abnormalities.
- Megakaryocytes had defective alpha-granule synthesis.
Conclusions:
- Gray platelet syndrome is an autosomal dominant disorder.
- The primary defect involves deficient alpha-granule synthesis and content in platelets and megakaryocytes.
- Morphological abnormalities in platelets are associated with the alpha-granule deficiency.
Abstract:
The ultrastructure and functions of platelets and megakaryocytes in 8 patients of a family with gray platelet syndrome were investigated. Hemostatic examinations on these patients revealed prolonged bleeding time, decreased platelet retention rates and decreased platelet aggregation rates induced by ADP, collagen, Ristocetin and epinephrine. Marked decreases in ATP and ADP release in response to these agents were also noted. Clinical and coagulation studies on this family suggested that the hereditary nature of the syndrome is autosomal dominant. Platelets and megakaryocytes in the peripheral and bone marrow blood smear from the patients showed peculiar gray color by May-Giemsa stain due to a deficiency of alpha-granules. Electron microscopic examinations revealed slightly enlarged platelets containing a deficient amount of alpha-granules, whereas dense bodies and mitochondria appeared normal. Several morphological abnormalities of patient's platelets, such as aggregates of dense tubular systems, circular arrays of dense tubular systems, an area of cytoplasmic sequestration with an enclosing membrane, clumps of dense material and remnants of Golgi apparatuses were recognized. Megakaryocytes showed normally developed Golgi zones, defective alpha-granule synthesis and liberation of abnormal platelets as shown in the peripheral blood smear.