Glanzmann's thrombasthenia
| Glanzmann's thrombasthenia | |
|---|---|
| Classification and external resources | |
| Specialty | hematology |
| ICD-10 | D69.1 |
| ICD-9-CM | 287.1 |
| OMIM | 187800 273800 |
| DiseasesDB | 5224 |
| MedlinePlus | 001305 |
| eMedicine | med/872 |
| MeSH | D013915 |
Glanzmann's thrombasthenia is an abnormality of the platelets. It is an extremely rare coagulopathy (bleeding disorder due to a blood abnormality), in which the platelets contain defective or low levels of glycoprotein IIb/IIIa (GpIIb/IIIa), which is a receptor for fibrinogen. As a result, no fibrinogen bridging of platelets to other platelets can occur, and the bleeding time is significantly prolonged.
Characteristically, there is increased mucosal bleeding:
The bleeding tendency is variable but may be severe. Hemarthrosis, particularly spontaneous, is very rare, in contrast to the hemophilias.
Platelet numbers and morphology are normal. Platelet aggregation is normal with , but impaired with other agonists such as ADP, thrombin, collagen or epinephrine.
Glanzmann's thrombasthenia can be inherited in an autosomal recessive manner or acquired as an autoimmune disorder.
The bleeding tendency in Glanzmann's thrombasthenia is variable, some individuals having minimal bruising, while others have frequent, severe, potentially fatal hemorrhages. Moreover, platelet αIIbβ3 levels correlate poorly with hemorrhagic severity, as virtually undetectable αIIbβ3 levels can correlate with negligible bleeding symptoms, and 10%–15% levels can correlate with severe hemorrhage. Unidentified factors other than the platelet defect itself may have important roles.
Glanzmann's thrombasthenia is associated with abnormal integrin αIIbβ3, formerly known as glycoprotein IIb/IIIa (GpIIb/IIIa), which is an integrin aggregation receptor on platelets. This receptor is activated when the platelet is stimulated by ADP, epinephrine, collagen, or thrombin. GpIIb/IIIa is essential to blood coagulation since the activated receptor has the ability to bind fibrinogen (as well as von Willebrand factor, fibronectin, and vitronectin), which is required for fibrinogen-dependent platelet-platelet interaction (aggregation).
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