Objective       To investigate the effect of UDP-glucuronosyltransferase 1A1 (UGT1A1) genetic mutant P364L (c.1091 CT) on the glucuronidation of unconjugated bilirubin.       Methods       The UGT1A1 wild-type and mutant P364L gene sequences were inserted into plasmid pEZ-M03 respectively

and then transfected into HEK293 cells. Western blotting was applied to test the expression of wild-type and mutant P364L-UGT1A1 proteins. Ultrasound was used to extract the intra-cellular compounds. High-performance liquid chromatography (HPLC) was used to detect the level of unconjugated bilirubin in both wild-type and mutant P364L  catalytic  reaction.       Results       The concentration of unconjugated bilirubin was significantly decreased while the peak concentration of conjugated bilirubin was increased over time in wild-type UGT1A1 catalytic reaction. However

the concentration of unconjugated bilirubin was slightly decreased over time and the peak concentration of conjugated bilirubin was not obviously detected in P364L-UGT1A1 catalytic reaction. The mutant P364L-UGT1A1 contained only 14.2% of wild-type enzyme activity.       Conclusion       Mutant P364L-UGT1A1(1091CT) has significantly lower enzyme activity to catalyze unconjugated bilirubin than wild-type UGT1A1.