The congenic normal R/APfd and jaundiced R/APfd-j/j rat strains: a new animal model of hereditary non-haemolytic unconjugated hyperbilirubinaemia due to defective bilirubin conjugation.

In this paper the production of the R/APfd-j/j strain which is congenic with the R/APfd strain is reported. The R/APfd-j/j completely lacks hepatic bilirubin UDP-glucuronyltransferase activity, as do our GUNNXR/Pfd-j/j rat strain and various other stocks of GUNN rats (j/j) described in the literature. Our recombinant inbred strain GUNNXR/Pfd-j/j was produced from non-inbred GUNN (j/j) rats. This GUNNXR/Pfd-j/j rat was used as a donor of the jaundice gene j, the R/APfd rat serving as the recipient. After eight backcross-intercross cycles (16 generations) the R/APfd-j/j strain was obtained which is congenic with the R/APfd strain. Congenicity was demonstrated by various techniques including transplantation of skin tissue, strain-specific tumour cells and hepatocytes, the mixed lymphocyte reaction, and comparison of biochemical markers. The potential of the novel inbred strain of jaundiced rat, R/APfd-j/j, and the corresponding control strain R/APfd for biochemical and clinical studies of bilirubin metabolism are briefly discussed.