Pharmacokinetic factors are critical: 6-MP is metabolized in the liver via xanthine oxidase and thiopurine methyltransferase (TPMT), and impaired hepatic function may reduce drug clearance, leading to the accumulation of toxic metabolites.[26] Given the patient’s baseline hepatic vulnerability, the risk of severe liver injury associated with 6-MP, such as fulminant hepatitis or worsening cirrhosis, outweighed its potential benefits. The gene discussed is XDH; the disease is Cirrhosis.