- Загальні відомості про тромботичні захворювання
- Антифосфоліпідний синдром (АФС)
- Дефіцит антитромбіну
- Підвищені рівні факторів VIII, IX та XI
- Гіпергомоцистеїнемія
- Резистентність фактора V до активованого протеїну C (APC)
- Дефіцит протеїну C
- Дефіцит протеїну S
- Дефіцит протеїну Z
- Мутація гена 20210 протромбіну (фактора II)
Because protein Z helps inactivate coagulation factor Xa, deficiency or dysfunction of protein Z predisposes to venous thrombosis (mainly in patients who also have other clotting abnormalities).
(See also Overview of Thrombotic Disorders.)
Protein Z, a vitamin K–dependent protein, functions as a cofactor to down-regulate coagulation by forming a complex with the plasma protein, Z-dependent protease inhibitor (ZPI). The complex predominantly inactivates factor Xa on phospholipid surfaces.
The consequence of protein Z or ZPI congenital deficiency, or of acquired autoantibodies to protein Z, in the pathophysiology of thrombosis, fetal loss, and cancer (ovarian or gastric) is not completely clear; however, a defect of either protein Z or ZPI may make thrombosis more likely if an affected patient also has another congenital coagulation abnormality (eg, factor V Leiden) or an acquired autoantibody against a phospholipid-bound protein (an antiphospholipid antibody).
Testing for protein Z deficiency is not part of routine thrombophilia testing. Quantification of protein Z, ZPI, and protein Z autoantibodies is done in specialized regional laboratories by plasma electrophoresis, immunoblotting, and enzyme-linked immunosorbent assay.
It is not yet known whether anticoagulant therapy or prophylaxis is indicated in protein Z or ZPI deficiency.
