Moreover, he developed mild cholestatic liver disease (AST: 72 IU/L, ALT: 45 IU/L, total bilirubin: 4.5 mg/dL, and direct bilirubin: 1.6 mg/dL) with hyperammonemia (177 μmol/L) and hyperargininemia (1402 μmol/L). The gene discussed is GPT; the disease is Hyperammonemia.