UGT1A1 and Gilbert syndrome: Inherited unconjugated hyperbilirubinemia is caused by pathogenic variants in the UGT1A1 gene and, depending on the bilirubin levels, is categorized as Gilbert’s syndrome (GS; OMIM: 143500), Crigler-Najjar syndrome type I (CNS-I; OMIM: 218800), or Crigler-Najjar syndrome type II (CNS-II; OMIM: 606785); the total bilirubin levels range from 17.1–102.6 μmol/L, 102.6–342 μmol/L, and 342–769.5 μmol/L, respectively [1].