UGT1A1 and Crigler-Najjar syndrome: Crigler-Najjar syndrome type I (CN1, MIM#218800), Crigler-Najjar syndrome type II (CN2, MIM# 606785), and Gilbert syndrome (GS, MIM# 143500) are a group of hereditary unconjugated hyperbilirubinemias resulting from mutations within the UDP glucuronosyltransferase family 1 member A1 (UGT1A1) gene, located on chromosome 2q37 locus [1].