Disorders of Hemostasis and Thrombosis

Maintenance of vascular integrity is critical to all higher organisms and requires a delicate balance between pro- and anticoagulants to avoid pathologic thrombosis or hemorrhage. Deficiencies of primary (von Willebrand factor, platelets) or secondary (coagulation cascade) hemostasis lead to abnormal bleeding, while deficiency in the natural anticoagulants (proteins C, S, antithrombin) predispose to thrombosis. Disorders of fibrinolysis, the proteolytic cascade leading to dissolution of fibrin clots, are rarer and typically lead to overactivity and pathologic bleeding. Studies of rare human genetic disease and common variation has led to substantial advances in our understanding of these systems. In this chapter we review the biology of coagulation followed by discussion of known associated disorders.