Thrombosis in inherited factor VII deficiency.

Thrombosis in congenital factor (F) VII deficiency was investigated through extensive phenotypic and molecular-genetic studies. Patients with a history of thrombosis among 514 entries in the FVII Deficiency Study Group database were evaluated. Thrombotic events were arterial in one case, disseminated intravascular coagulation in another and venous in seven. Gene mutations were characterized in eight patients: three were homozygous, three compound heterozygous and two heterozygous. FXa and IIa generation assays were consistent with the genetic lesions. One patient was heterozygous for the FV Leiden and one for the FIIG20210A mutation. In seven patients, surgical interventions and/or replacement therapies had a close temporal relationship with thrombosis, while in the remaining, events were apparently spontaneous. Thromboses were not associated with any specific age, phenotype, mutation zygosity or thrombophilic abnormalities. In particular, severe FVII deficiency did not seem to offer protection from strong thrombosis risk factors such as surgery and replacement therapy.