GPT and metabolic dysfunction-associated steatotic liver disease: To further investigate whether specific N-glycan traits may be causally associated with biomarkers of liver physiology, we conducted additional bidirectional Mendelian randomization (MR) analyses between N-glycans and five phenotypes that reflect distinct aspects of liver function: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), and non-alcoholic fatty liver disease (NAFLD) (Supplementary Data 16a).