A large population-based study was conducted on 4582 adult participants without viral hepatitis, hemochromatosis, or alcoholic liver disease, from the National Health and Nutrition Examination Survey (NHANES) in 2003-2004, to investigate whether environmental pollutants are associated with an elevation in serum ALT and suspected NAFLD. The gene discussed is GPT; the disease is metabolic dysfunction-associated steatotic liver disease.