Fibrinogen gamma chain

Fibrinogen gamma chain (FGG) is a 51.5 kDa protein that functions as a key structural component of blood clots, polymerizing with fibrinogen alpha and beta chains to form insoluble fibrin matrices (UniProt: P02679). Beyond hemostasis, it plays roles in wound repair, platelet activation, and immune responses to infection, including antibacterial defense via both innate and T-cell-mediated pathways.

FGG is primarily associated with blood coagulation and hemostasis. Genetic mutations cause rare bleeding disorders: congenital afibrinogenemia (OMIM 202400) and congenital dysfibrinogenemia (OMIM 616004), which present with variable bleeding severity and thrombotic complications (UniProt: P02679).

In Alzheimer's Disease, FGG is significantly upregulated in post-mortem AD brain tissue compared to age-matched controls. Quantitative proteomics analysis using tandem mass tagging across four subcellular fractions detected a mean log2 fold-change of +1.229 (Chaparral AD proteomics). This elevated brain fibrinogen levels in AD suggests potential involvement in neuroinflammatory or thrombotic pathways associated with neurodegeneration, though functional relevance remains to be determined.