G20210A

G20210A refers to a single nucleotide change in the prothrombin gene (F2), a G to A substitution at nucleotide position 20210 in the 3' untranslated region. This polymorphism is associated with mildly increased plasma levels of prothrombin, which can enhance thrombin generation and promote a hypercoagulable state. It is one of the common inherited thrombophilias and is usually inherited in an autosomal dominant pattern with incomplete penetrance; heterozygotes have a modest risk, while homozygotes are rarer and carry a higher risk of thrombosis.

Carrier frequency varies by ethnicity, being most common in people of European descent with estimates around 2-3% in some populations.

Clinically, G20210A is associated with an increased lifetime risk of venous thromboembolism, including deep vein thrombosis and pulmonary embolism. The risk is higher with additional factors such as surgery, immobilization, estrogen therapy, pregnancy, and obesity. The evidence linking G20210A to arterial thrombosis or bleeding is limited.

Diagnosis is via genetic testing, typically using PCR-based assays or sequencing to detect the G to A substitution at 20210 in F2. It is often evaluated as part of a thrombophilia workup in individuals with unprovoked VTE or a family history of thrombosis.

Management focuses on risk reduction and context-dependent treatment. Carriers without a history of VTE generally do not require long-term anticoagulation but should consider risk mitigation during high-risk situations (eg, surgery, pregnancy). Those with prior VTE may require standard anticoagulation and possibly extended therapy based on individual risk.