The hepatic steatosis index (HSI), calculated on the basis of the serum aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio, body mass index (BMI), sex, and presence of diabetes mellitus, has been validated in a large cohort of more than 10,000 patients [19] and adopted as a screening method for NAFLD [20, 21]. This evidence concerns the gene GPT and fatty liver disease.