Fibrinogen alpha chain (FGA) antibodies are autoantibodies targeting the alpha subunit of fibrinogen, a critical glycoprotein involved in blood coagulation and wound healing. Fibrinogen, synthesized primarily in the liver, circulates in plasma as a hexamer composed of two sets of three polypeptide chains (Aα, Bβ, and γ). During clot formation, thrombin cleaves fibrinogen, releasing fibrinopeptides and generating fibrin monomers that polymerize into a mesh, stabilizing blood clots.
FGA antibodies are implicated in various pathological conditions. In autoimmune disorders like anti-phospholipid syndrome (APS), these antibodies may disrupt fibrinogen’s normal function, contributing to thrombotic events or bleeding complications. They are also associated with rare fibrinogen deficiencies (e.g., afibrinogenemia or hypofibrinogenemia), where mutations in the *FGA* gene lead to abnormal protein expression, triggering immune responses. Additionally, FGA autoantibodies have been observed in certain cancers, inflammatory diseases, and liver pathologies, possibly due to aberrant fibrinogen processing or exposure of cryptic epitopes.
Clinically, detecting FGA antibodies aids in diagnosing fibrinogen-related disorders and guiding therapeutic strategies, such as immunosuppression or fibrinogen replacement. Research continues to explore their role in disease mechanisms and potential as biomarkers for thrombosis or autoimmune activity.