A genetic test can be performed to determine whether you have the genetic mutation and whether you have the mutated gene and whether you have one or two mutated genes. This test can be performed in combination with another test option to determine whether your blood is resistant to activated protein C, one of the anti-clotting proteins that help control factor V. This is known as an activated protein C (APC) resistance assay.  Normal results would show that the blood is not resistant to APC and therefore any abnormal blood clots are not likely to be caused by the factor V Leiden mutation.

If your blood is resistant to activated protein C, you likely have a mutation in the factor V gene. 95% of people resistant to activated protein C have the factor V Leiden mutation. A follow-up test to consider is the Factor V (Leiden) DNA Mutation Analysis with Reflex to HR2 Mutation Analysis.