Crigler-Najjar syndrome type I (CN-I) is a rare autosomal recessive disorder caused by mutations in the UGT1A1 gene, leading to a deficiency of bilirubin-UDP-glucuronosyltransferase and resulting in severe unconjugated hyperbilirubinemia. This evidence concerns the gene UGT1A1 and Crigler-Najjar syndrome type 1.