Thrombin generation in FV-deficient plasma reconstituted with normal FV and/or FV_Leiden. Congenitally FV-deficient plasma was reconstituted with purified normal FV and/or FV_Leiden to simulate normal plasma (Δ), FV_Leiden-heterozygous plasma (○), FV_Leiden-homozygous plasma (•), and FV_Leiden-pseudohomozygous plasma (⋄). Thrombin generation after extrinsic activation of plasma in the absence (A) and presence (B) of 20 nM APC was measured as described in “Materials and methods.”