Lucey-Driscoll Syndrome is due to which mechanism?

• A. Circulating maternal inhibitor of bilirubin conjugation
• B. Viral infection of the liver
• C. Increased hepatic UDPGT activity
• D. Biliary obstruction

Answer: (A)

Lucey-Driscoll syndrome involves a temporary drop in the newborn’s ability to conjugate bilirubin because a factor from the mother interferes with the conjugation process. Bilirubin is normally made water-soluble for excretion by hepatic UDP-glucuronosyltransferase, which adds glucuronic acid to bilirubin. In this syndrome, circulating maternal inhibitors cross to the baby and inhibit this enzyme, so unconjugated bilirubin accumulates in the blood, causing jaundice. As the maternal factor clears from the infant’s circulation after birth, UDP-glucuronosyltransferase activity normalizes and bilirubin conjugation resumes.

This differs from a viral infection of the liver, which would imply hepatocellular injury with different signs and enzyme changes; biliary obstruction would cause a rise in conjugated bilirubin and typically pale stools; and increased UDP-glucuronosyltransferase activity would enhance conjugation, not produce hyperbilirubinemia.