Characterization of the homozygous Budapest-III patients. (A) Pedigree of the thrombophilic family. Filled symbols indicate homozygous carriers, and half-filled symbols indicate heterozygous carriers. Anti-FXa activity values and the age of the first thrombotic episode (in brackets) are also indicated. N.D. indicates those cases where anti-FXa activity was unknown. N.D. indicates nondetermined; PE, pulmonary embolism; VBIS, vertebral-basilar ischemic stroke; and DVT, deep venous thrombosis. (B) Crossed immunoelectrophoresis in the presence of unfractionated heparin of the plasma of homozygous and heterozygous Budapest-III patients and control plasma. The antithrombin forms of high and low heparin affinity are indicated. (C) Electropherogram of the PCR-amplified product of exon 2 in a control, a heterozygous patient, and a homozygous patient for the L99F mutation. ↓ indicates the position of the mutation.