Fibrinogen alpha chain

Fibrinogen alpha chain (FGA) is a 866-amino acid serum glycoprotein that serves as the precursor to fibrin, a critical component of blood clots (UniProt: P02671). Upon cleavage by thrombin, fibrinogen monomers polymerize with fibrinogen beta and gamma chains to form an insoluble fibrin matrix essential for hemostasis and wound repair. Beyond coagulation, fibrinogen modulates platelet activation, supports immune responses, and protects against hemorrhage during infection.

Fibrinogen alpha is primarily synthesized in the liver and circulates in blood plasma. Genetic variants and dysfunction are associated with congenital afibrinogenemia (complete fibrinogen absence), hereditary systemic amyloidosis characterized by renal fibrin deposition, and congenital dysfibrinogenemia with variable bleeding or thrombotic phenotypes (UniProt: P02671).

In Alzheimer's disease, fibrinogen alpha chain is upregulated in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of 1.49 (Chaparral AD proteomics). This elevation was observed in human post-mortem brain via TMT-labeled proteomics across subcellular fractions, suggesting fibrinogen involvement in AD-associated pathology, potentially related to neuroinflammation, vascular dysfunction, or amyloid-associated processes.