Carbonic anhydrase 6 (CA6), also known as gustin, is a salivary enzyme that catalyzes the reversible hydration of carbon dioxide 1. CA6 plays important roles in oral homeostasis, including taste perception, dental tissue protection against mineral loss, and caries prevention 1. The gene exhibits functional genetic polymorphisms that influence salivary CA6 protein concentration; individuals with the TT genotype at rs2274327 show significantly lower CA6 levels than those with CT or CC genotypes 1. CA6 polymorphisms, particularly rs2274333 (A/G), mechanistically link to fungiform papilla density and PROP taste sensitivity by affecting cell proliferation and metabolic activity 2. The CA6 A/A genotype is associated with increased bitter taste perception 3, though associations with salt taste perception have also been reported 3. Regarding disease relevance, CA6 polymorphisms show modest associations with dental caries susceptibility 4 and combined bitter taste gene variants correlate with altered breast cancer risk 5. Notably, plasma CA6 levels are inversely associated with peripheral artery disease risk in individuals with type 2 diabetes, suggesting protective vascular effects 6. These findings indicate CA6 functions beyond taste, potentially affecting systemic disease susceptibility through mechanisms requiring further investigation.