Factor VII Deficiency: From Basics to Clinical Laboratory Diagnosis and Patient Management.

Factor VII (FVII) deficiency is a rare inheritable bleeding disorder affecting 1/500 000 individuals. Clinical manifestations are heterogeneous, from asymptomatic to severe and potentially fatal bleeding. These clinical manifestations do not correlate well with FVII plasma levels. For this reason, FVII-deficient patient management during surgery or for long-term prophylaxis remains challenging. Laboratory testing for FVII activity is, however, the first-line method for FVII deficiency diagnosis and is helpful for managing patients in combination with clinical history. Additional testing consists of FVII immunoassay and genetic testing. Genetic abnormalities on the FVII gene are heterogeneous and can translate into quantitative or qualitative defects. Some of the latter can react differently with different thromboplastins; this can be misleading for the laboratory as no consensus exists at present on an FVII deficiency diagnosis methodology. Indeed, no single test is able to predict accurately the bleeding risk. This review provides a broad picture of inherited and acquired FVII deficiency with a particular focus on laboratory diagnosis.