Genetic variation in the uridine diphosphate glucuronosyltransferase 1A1 gene (UGT1A1) is the major cause of hyperbilirubinemia (Johnson et al., 2009; Fujiwara et al., 2018) and is therefore suitable for exploring whether elevated bilirubin levels is a direct cause of reduced risk of NAFLD using a Mendelian randomization approach. The gene discussed is UGT1A1; the disease is Hyperbilirubinemia.