GPT and disorder of methionine catabolism: This revealed isolated plasma hypermethioninemia at 985 μmol/L (normal 10–60) and high urine methionine/creatinine ratio at 46 μmol/mmol (normal 3–10), mildly elevated plasma homocysteine level 15 μmol/L (normal 5–10), and elevation of muscle enzymes with elevated ALT 250 IU/L (normal 5–25) and high CK 1450 IU/L (normal <250).