The Factor V Leiden (p.Arg506Glu Gene Mutation) test is performed to detect a genetic change in the Factor V gene that results in the p.Arg506Glu mutation. This mutation changes the structure of factor V during blood clotting, making it less likely to be broken down by Protein C, an important factor in stopping blood clotting. This results in an increased risk of abnormal blood clotting, a condition called thrombosis.