What genetic condition is characterized by symptomatic jaundice and increased indirect bilirubin due to an absence of glucuronosyltransferase?

The genetic condition characterized by symptomatic jaundice and increased indirect bilirubin due to an absence of glucuronosyltransferase is Crigler-Najjar syndrome. This condition is specifically caused by a deficiency in the enzyme UDP-glucuronosyltransferase, which is responsible for converting indirect (unconjugated) bilirubin into conjugated bilirubin. When this enzyme is deficient or absent, indirect bilirubin accumulates in the bloodstream, leading to jaundice.

In Crigler-Najjar syndrome, there are two types: Type I is severe and presents with very high levels of unconjugated bilirubin, while Type II is less severe and can often be managed with treatment. The presence of symptoms like jaundice and elevated indirect bilirubin levels is a hallmark of this syndrome.

Other conditions mentioned, such as Dubin-Johnson syndrome and Gilbert syndrome, have different mechanisms. Dubin-Johnson syndrome involves a defect in the hepatic excretion of conjugated bilirubin, leading to an increase in direct bilirubin rather than indirect. Gilbert syndrome, on the other hand, is a milder condition with a partial deficiency of the same enzyme, leading to elevated levels of unconjugated bilirubin but typically without severe symptoms.