A 5-month-old female is brought to the pediatrician for evaluation of
jaundice that began after a viral
upper respiratory tract infection. She was born at 39 weeks gestation to a 27-year-old, gravida 1 para 1, woman via
spontaneous vaginal delivery. The patient has been meeting
developmental milestones. Family history is noncontributory. Physical examination shows
scleral icterus and diffuse jaundice. Abdominal and neurological exams are unremarkable. Blood testing is performed and reveals the following:
| Laboratory value | Result |
| Hemoglobin | 13.9 mg.dL |
| Leukocyte count | 6,800/mm3 |
| Total bilirubin | 12.7 mg/dL |
| Conjugated bilirubin | 0.3 mg/dL |
| Alanine aminotransferase | 15 U/L |
| Aspartate aminotransferase | 16 U/L |
Phenobarbital is administered, and repeat total serum
bilirubin is measured at 7 mg/dL. Which of the following best describes the cause of this patient’s condition?
