DR Medhat MRCP

Thrombophilia ( = thrombotic tendency)
• Causes :
Inherited causes
Activated protein C resistance (factor V
Leiden)
Antithrombin III deficiency.
Protein C deficiency.
Protein S deficiency.
Hyperhomocyctienemia.
Acquired causes
Antiphospholipid syndrome.
Combined oral contraceptive pill
(COCP)
Pregnancy.
Smooking.
Obesity.
Malignancy .e.g MM
Past H/O venous
thromboembolism (DVT/PE).
Activated protein C resistance (factor V Leiden) is the commonest inherited thrombophilia
It is an autosomal dominant disorder.
The most common inherited thrombophilia is resistance to activated protein c
which lead to functional protein c abnormality , this results from mutation of
factor V gene ( leiden mutation) that renders factor V resistant to the modulating
effect (anti coagulant effect)of protein C ( normally , when the protein C is
activated ,it inhibits factor V & VII with the help of protein S anticoagulant
effect).
Antithrombin III Deficiency
- It is an inherited cause of thrombophilia occurring in approximately 1:2,000 of the
population. Inheritance is autosomal dominant
• Features :
Anti-thrombin III normally (- -) several clotting factors, primarily thrombin,
factor X and IX (- -) their coagulant effect .
Heparin works by binding to antithrombin III, enhancing its anticoagulant
effect by inhibiting the formation of thrombin and other clotting factors.
Patients with antithrombin III deficiency may therefore by resistant to
heparin treatment
Recurrent venous thromboses.
Arterial thromboses do occur but is uncommon
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