Prothrombin gene mutation refers to a change in the prothrombin gene, which is responsible for producing a protein essential for blood clotting. This mutation can lead to increased levels of prothrombin in the blood, raising the risk of abnormal blood clots, a condition known as thrombosis. Individuals with this mutation may not show symptoms until a clot forms, which can occur in veins or arteries. Testing for the prothrombin gene mutation is often done in people with a history of unexplained blood clots, helping to guide treatment and prevention strategies.