OBJECTIVE: To investigate the effect of donor-recipient CYP3 A5 gene polymorphisms on the tacrolimus concentration/dose ratio（ C/D） in the early postoperative period after liver transplantation. METHODS:Seventy-one patients who received liver transplantation for the first time at Beijing Tsinghua Changgung Hospital

School of Clinical Medicine

Tsinghua University in 2020 were retrospectively collected. Tacrolimus dose at 2

3 and 4 weeks after surgery and blood concentration（ C） at corresponding time points were recorded to obtain daily dose per kilogram（ D）

and C/D value was calculated respectively. The genotypes of donor-recipient CYP3 A5 were determined by fluorescence in situ hybridization

and CYP3 A5

*

1/

*

1 and CYP3 A5

*

1/

*

3 were grouped according to genotype

and CYP3 A5

*

3/

*

3 were grouped as the expression group and CYP3 A5

*

3/

*

3 were grouped as the non-expression group

the effects of donor-recipient genotype on C/D value were analyzed separately and jointly

meanwhile

the donor-recipient genotypes were analyzed to compare the normal recovery rate of liver function after liver transplantation. RESULTS: At 2

3 and 4 weeks after surgery

C/D values were lower in both donor and recipient expressing group than in the non-expressing group

with statistically significant differences（ P

<

0. 05）. C/D values of donor non-expression/receptor non-expression group were higher than those of donor expression/receptor expression group

donor expression/receptor non-expression group and donor non-expression/receptor expression group

the difference was statistically significant（ P

<

0. 05）. At 1 month after surgery

there was no significant difference in the normal rate of liver function between donor expression/receptor expression group

donor expression/receptor nonexpression group

donor non-expression/receptor expression group and donor non-expression/receptor non-expression group（ P

>

0. 05）. CONCLUSIONS: Both donor-recipient CYP3 A5 gene polymorphisms are genetic factors affecting tacrolimus C/D in patients after liver transplantation. Patients carrying CYP3 A5

*

3/

*

3 may require a lower dose to achieve the same target blood concentration

Genotype testing before medication can more effectively guide the clinical application of tacrolimus.