Antithrombin deficiency, congenital

A genetic disorder affecting blood clotting

Congenital Antithrombin Deficiency
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Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Increased risk of venous thromboembolism
Complications	Deep vein thrombosis, pulmonary embolism
Onset
Duration
Types	N/A
Causes	Genetic mutations
Risks	Family history
Diagnosis	Blood test for antithrombin activity
Differential diagnosis	N/A
Prevention	N/A
Treatment	Anticoagulant therapy
Medication	N/A
Prognosis	N/A
Frequency	Rare
Deaths	N/A

Congenital Antithrombin Deficiency is a genetic disorder characterized by a deficiency in antithrombin, a protein in the blood that helps regulate blood clotting. This condition leads to an increased risk of developing venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE).

Pathophysiology

Antithrombin is a serine protease inhibitor (serpin) that inactivates several enzymes of the coagulation cascade, particularly thrombin and factor Xa. In individuals with congenital antithrombin deficiency, mutations in the SERPINC1 gene lead to reduced levels or dysfunctional antithrombin, impairing its ability to regulate clot formation. This imbalance results in a hypercoagulable state, predisposing affected individuals to thrombotic events.

Genetics

Congenital antithrombin deficiency is typically inherited in an autosomal dominant manner, meaning a single copy of the mutated gene can cause the disorder. However, the severity of the condition can vary depending on whether the individual is heterozygous or homozygous for the mutation. Homozygous individuals often experience more severe symptoms and earlier onset of thrombotic events.

Clinical Presentation

Patients with congenital antithrombin deficiency may present with recurrent episodes of venous thromboembolism, often at a young age. Common sites of thrombosis include the deep veins of the legs and the pulmonary arteries. Symptoms of DVT include swelling, pain, and redness in the affected limb, while PE may present with shortness of breath, chest pain, and hemoptysis.

Diagnosis

Diagnosis of congenital antithrombin deficiency is confirmed through laboratory testing. A blood test measuring antithrombin activity is typically performed. Levels below 80% of normal activity suggest a deficiency. Genetic testing can identify specific mutations in the SERPINC1 gene.

Management

Management of congenital antithrombin deficiency focuses on preventing thrombotic events. Long-term anticoagulant therapy, such as warfarin or direct oral anticoagulants (DOACs), is often prescribed. In high-risk situations, such as surgery or pregnancy, additional prophylactic measures may be necessary. Patients are also advised to avoid risk factors for thrombosis, such as smoking and prolonged immobility.

Prognosis

With appropriate management, individuals with congenital antithrombin deficiency can lead normal lives. However, they remain at increased risk for thrombotic events, particularly if anticoagulation is interrupted or in high-risk situations.

Also see

• Thrombophilia
• Protein C deficiency
• Protein S deficiency
• Factor V Leiden
• Venous thromboembolism