The liposomal system containing the human uridinediphosphoglucuronate glucuronosyltransferase-1A1 gene (hUGT1A1) was administered through i.v. route into UGT1A1-deficient hyperbilirubinemic Gunn rats (model of Crigler-Najjar syndrome type 1). Here, UGT1A1 is linked to Crigler-Najjar syndrome type 1.