[Immune-mediated acquired coagulation factor deficiencies: state-of-the-art in diagnosis and management]

Recently, in Japan, the number of patients with autoimmune acquired coagulation factor deficiency (AiCFD) due to anti-coagulation factor autoantibodies has been on the rise. There are several types of such autoantibodies, which can be generated against any coagulation factor: 1) the neutralizing type binds the functional region (s) of a coagulation factor to inhibit its activity (inhibitor type) ; 2) the non-neutralizing type binds the nonfunctional region (s) of a coagulation factor and enhances its clearance from circulation (hyperclearance type) ; 3) the combination of types 1) and 2). Despite clinical manifestations of AiCFD ranging from asymptomatic laboratory abnormalities to fatal exsanguination or even to thromboembolic events, most patients with AiCFD exhibit certain bleeding symptoms. Owing to the major bleeding symptoms of AiCFD not being specific for any particular disease, laboratory tests are essential for the early diagnosis of AiCFD, selection of proper treatment, and assessment of a therapy's efficacy. Because of severe ongoing hemorrhages and anemia, most patients are administered large amounts of the deficient coagulation factors. Moreover, given the rarity of this disease, there is no standardized therapeutic modality for antibody eradication. Most patients receive corticosteroids as first-line immunosuppressive medicines; however, some patients become treatment-resistant or develop a recurrence despite achieving remission once.