Gilbert syndrome is a hereditary, relatively common, benign, unconjugated hyperbilirubinaemia (high bilirubin levels in the blood).
Gilbert syndrome is generally considered to be an autosomal recessive disorder. However, there have been cases of heterozygosity and compound heterozygosity reported in patients with Gilbert syndrome, particularly among the Asian population.
The characteristics of Gilbert syndrome are normal liver function tests of the usual type, normal liver histology, delayed clearance of bilirubin from the blood, and mild jaundice that tends to fluctuate in severity, particularly after fasting. This disorder is difficult to distinguish from prolonged posthepatic hyperbilirubinaemia.
Patients with Gilbert syndrome tend to have total serum bilirubin levels from 1-6 mg/dL. This is distinguished from Crigler-Najjar syndrome type II, in which patients have total serum bilirubin levels between 6 and 20 mg/dL, and Crigler-Najjar syndrome type I, in which patients have total serum bilirubin levels from 20 to 45 mg/dL.