Serum GDCA was significantly elevated in gallstone mice (p = 0.029), and calculated ratios-including the secondary/primary bile acid ratio (p < 0.001) and the glycine/taurine conjugation ratio (p = 0.004)-were increased (Figure 7C), suggesting enhanced microbiota-mediated bile acid transformation and greater lithogenic potential. Here, GNAT3 is linked to gallstones.