28-year-old man, emigrated from the Philippines Positive tuberculin skin test No active tuberculosis Symptoms: weight loss, cough, and night sweats Treatment: daily dose of isoniazid for 9 months Two weeks later: report of progressive fatigue, intermittent bouts of nausea, abdominal pain, darkened urine, light colored stools. The patient's sister noticed yellowing of his eyes and skin. Blood test: Increase in serum bilirubin and aminotransferases. The isoniazid was discontinued, and patient's symptoms subsided. Cause of Condition? Diagnosis?