You are treating a 5-day-old infant who is suffering from severe jaundice with serum indirect bilirubin levels of 21 mg/dL. Given the age of onset and the severity of the hyperbilirubinemia in this infant, which of the following would represent the most likely diagnosis?

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Quizplus · Accepted Answer

Crigler-Najjar syndrome, type 1 is characterized by severe unconjugated hyperbilirubinemia in the neonatal period due to a deficiency of the enzyme UDP-glucuronosyltransferase, leading to very high levels of indirect bilirubin. There are 2 forms of Crigler-Najjar syndrome: type I results from mutations in the bilirubin-UDPglucuronyltransferase gene that result in complete loss of enzyme activity, whereas type II is the result of mutations that cause incomplete loss of enzyme activity. In patients with very high levels of indirect-reacting (unconjugated) bilirubin in the plasma, but with normal liver function tests, Crigler-Najjar syndrome type I is indicated. Almost all afflicted infants manifest with severe nonhemolytic icterus within the first few days of life.

You Are Treating a 5-Day-Old Infant Who Is Suffering from Severe