Structural and functional disruption of fibrinogen by a novel FGG c.1099G > C (p.Ala367Pro) variant: an integrated in silico mechanistic study.

This study aimed to elucidate the molecular pathogenesis of the novel FGG p.Ala367Pro variant, recently identified in a patient with congenital dysfibrinogenemia (CD), using an integrated in silico approach. A comprehensive computational pipeline was applied. Pathogenicity was evaluated using MutationTaster, PolyPhen-2, PROVEAN, and VarCards. Structural effects were modeled with AlphaFold3 and analyzed via PyMOL. Protein stability was assessed using Missense3D, DUET, MUpro, DynaMut2, and I-Mutant2.0. Evolutionary conservation was evaluated using ConSurf and Clustal X. The p.Ala367Pro variant was consistently predicted to be deleterious by all pathogenicity prediction tools. Structural modeling indicated that the alanine-to-proline substitution predicteda local alpha-helix and abolishes a key hydrogen bond, leading to significant destabilization of the γ-chain tertiary structure (consistently negative ΔΔG values across stability prediction tools). The Ala367 residue was found to be perfectly conserved across species. These findings support a potentially mechanistic that the FGG p.Ala367Pro mutation is a pathogenic variant that disrupts fibrinogen function by compromising γ-chain stability and structure. Our work establishes a in silico framework for the functional validation of novel fibrinogen variants, crucial for interpreting genetic findings and guiding clinical management in CD.