MTX: methotrexate; AST: aspartate aminotransferase; ALT: alanine aminotransferase; RA: rheumatoid arthritis; SWE: shear wave elastography; JIA: juvenile idiopathic arthritis; DMARD: disease-modifying antirheumatic drug; LE: liver enzyme; LB: liver biopsy; BMI: basal metabolic index. The gene discussed is GPT; the disease is juvenile idiopathic arthritis.