A 4-year-old girl presented with the chief complaint of jaundice and failure to thrive. At birth, she weighed 1.7 kg. Neonatal jaundice and ascites were present, but resolved in 2 weeks. She was discharged from the hospital at age 5 weeks weighing 2.1 kg. She gained weight poorly and was readmitted at age 4 months. She was jaundiced. Laboratory values in serum were as follows: total bilirubin, 110 μmol/L (80% direct); alanine aminotransferase, 240 U/L; aspartate aminotransferase, 75 U/L; and ammonia, 160 μmol/L. Levels of urine and serum amino acids were also determined. She started on a low-protein diet and was discharged from the hospital.
She was unavailable for follow-up until presentation. At that time, her serum bilirubin level was 444 μmol/L. Two weeks after admission, she developed acute gastrointestinal bleeding. Laboratory values were as follows: platelet count, 35 × 109/L; serum ammonia, 125 μmol/L; alkaline phosphatase, 17.9