Which condition is indicated by the presence of severe jaundice at birth due to a defect in bilirubin metabolism?

The presence of severe jaundice at birth due to a defect in bilirubin metabolism is indicative of Crigler-Najjar syndrome. This condition is caused by a genetic deficiency of the enzyme UDP-glucuronosyltransferase, which is responsible for conjugating bilirubin in the liver. When this enzyme is lacking or deficient, unconjugated (indirect) bilirubin accumulates in the bloodstream, leading to jaundice.

In newborns, this accumulation can be particularly pronounced and can result in severe hyperbilirubinemia, which can cause complications like kernicterus if not treated promptly. Infants with Crigler-Najjar syndrome typically present with jaundice shortly after birth, and the severity can be markedly higher than in other conditions related to jaundice.

Understanding the contrast between this syndrome and other conditions is also important. For example, Gilbert's syndrome, while related to bilirubin metabolism, typically presents with mild, intermittent jaundice later in life rather than severe jaundice at birth, as it involves a partial deficiency of the same enzyme. Dubin-Johnson syndrome, on the other hand, is characterized by isolated conjugated hyperbilirubinemia due to a defective transport mechanism in the liver, and usually