Immunosuppressant drug metabolism gene testing

Immunosuppressant drug metabolism testing

Detection content

Based on the pharmacogenomic metabolism database and the latest literature research reports, 3 genes related to immunosuppressant drug metabolism on the genome, totaling 9 SNP sites (Table 1), were selected for genotyping testing and interpretation of their impact on drug metabolism. It has the advantages of comprehensiveness, accuracy, and high sensitivity.

Table 1. 9 SNPs related to immunosuppressant drug metabolism

Result Interpretation

Cytochrome P450 (CYP450 for short) represents a large family of self-oxidizing heme proteins and belongs to a class of monooxygenases. It is named after its specific absorption peak at 450nm of the light source. It is involved in the metabolism of endogenous substances and exogenous substances including drugs and environmental compounds. According to the degree of homology of amino acid sequences, its members are divided into three levels: family, subfamily and individual enzyme. The cytochrome P450 enzyme system can be abbreviated as CYP, where the family is represented by Arabic numerals, the subfamily is represented by capital English letters, and the individual enzymes are represented by Arabic numerals, such as CYP2D6, CYP2C19, CYP3A4, etc. At least 9 P450s in the human liver cytochrome P450 enzyme system are related to drug metabolism.

CYP3A gene: CYP3A is the most abundantly expressed enzyme in the CYP450 superfamily. It accounts for 30% of the entire CYP enzyme system in the liver and 70% in the intestine. It is involved in the metabolism of 40% to 60% of commonly used clinical drugs. The gene encoding CYP3A is located on chromosome 7 (7q21), and the main ones involved in the metabolism of tacrolimus are CYP3A4 (liver, small intestine, colon and pancreas) and CYP3A5 (small intestine and stomach).

rs4646437

CYP3A4 rs4646437C>T is related to the expression and activity of CYP3A4 protein^[1]. A study of 521 Chinese kidney transplant patients found that the cyclosporine (CsA) C/D ratio of patients with CYP3A4 rs4646437 CC genotype was significantly higher than that of patients with TT genotype (CC vs TT: 160.9±79.1 ng·ml -1 /mg·kg -1 vs 91.3±37.9 ng·ml -1 /mg·kg -1 )^[2]. A study of 382 Chinese kidney transplant patients found that the CYP3A4 rs4646437 mutation affects the plasma concentration/dose ratio of TAC (tacrolimus) (CC vs CT+TT, 2.08±0.02 vs 1.93±0.05; P=0.01)^[3]。

References:

[1] Sex-dependent genetic markers of CYP3A4 expression and activity in human liver microsomes.

[2] Influence of CYP3A and ABCB1 polymorphisms on cyclosporine concentrations in renal transplant recipients.

[3] IL-3 and CTLA4 gene polymorphisms may influence the tacrolimus dose requirement in Chinese kidney transplant recipients.

rs2740574

The mutation of rs2740574 is located in the 5' promoter region, mutating from A to G; mutation at this site will reduce the expression and activity of CYP3A4 protein^[1]. A pharmacokinetic study on 52 Tunisian kidney transplant patients taking TAC found that the C0/D ratio of TAC in the rs2740574 heterozygous genotype was significantly lower than that in the rs2740574 wild-type homozygous genotype (49.8 ± 19.9 vs 93.6 ± 30.3), whether in the early or late stages of transplantation.^[2]。

References:

[1] The cyp3a4*1b allele increases risk for small cell lung cancer: effect of gender and smoking dose.

[2] Influence of combined CYP3A4 and CYP3A5 single-nucleotide polymorphisms on tacrolimus exposure in kidney transplant recipients: a study according to the post-transplant phase.

rs2242480

A study of 382 Chinese kidney transplant patients found that the CYP3A4 rs2242480 mutation affects the plasma concentration/dose ratio (log value) of TAC (tacrolimus) (CC vs CT+TT, 2.08±0.02 vs 1.96±0.04; P=0.01)^[1]. A pharmacokinetic study of TAC in 46 Brazilian kidney transplant patients found that the CO/D ratio of TAC in patients with the rs2242480 AA homozygous mutation was significantly lower than the other two genotypes (AA: 0.8 ± 0.4 and GA: 1.3 ± 0.7 vs. GG: 2.6 ± 1.6 ng/mL/mg)^[2]。

References:

[1] IL-3 and CTLA4 gene polymorphisms may influence the tacrolimus dose requirement in Chinese kidney transplant recipients.

[2] Influence of CYP3A4 and CYP3A5 polymorphisms on tacrolimus and sirolimus exposure in stable kidney transplant recipients.

rs35599367

The mutation at this site occurs in the intron 6 region of the CYP3A4 gene. Studies have shown that this mutation will change the splicing mode of pre-mature mRNA, causing a 2-fold or more increase in non-functional RNA splicing variants in liver tissue, resulting in a decrease in the level of CYP3A4 transcribed mRNA and expressed protein.^[1]. In a pharmacokinetic study of 99 renal transplant patients (Netherlands) who were stable on tacrolimus (49 patients) or cyclosporine (50 patients), the study showed that heterozygous mutations (CT type) at this site increased the plasma concentration of tacrolimus (Tac) by 2-fold and cyclosporine (CsA) by 1.6-fold compared with the homozygous wild-type (CC). When the CYP3A4 and CYP3A5 genotypes were studied together, it was found that the weak metabolome of the CYP3A gene (rs35599367 C>T, rs776746 GG) compared with the intermediate metabolizer group (rs35599367 CC, rs776746 GG) increased the blood Tac concentration by 1.6 times and the CsA concentration by 1.5 times; compared with the strong metabolizer group (rs35599367 CC, rs776746 C>G), the Tac concentration increased by 4.1 times and the CsA concentration increased by 2.2 times.^[2]。

References:

[1] CYP3A4 intronic SNP rs35599367 (CYP3A4*22) alters RNA splicing.

[2] Effect of a new functional CYP3A4 polymorphism on calcineurin inhibitors' dose requirements and trough blood levels in stable renal transplant patients.

rs776746

There are many studies on this site, and there are relatively clear conclusions: wild-type AA (CYP3A5*1/*1): fast metabolism; heterozygous mutation AG (CYP3A5*1/*3): fast metabolism; homozygous mutation GG (CYP3A5*3/*3): slow metabolism.

rs15524

A pharmacokinetic study of TAC and SRL (sirolimus) in 46 Brazilian kidney transplant patients found that the CO/D values of these two drugs in patients with the rs15524 TT genotype were higher than those in patients with the CT CC genotype^[1]. A study on 51 Brazilian kidney transplant patients showed that the genotype of rs15524 carrying C (CC CT) can accelerate the metabolism of TAC and reduce the plasma concentration of TAC.^[2]。

References:

[1] Effect of a new functional CYP3A4 polymorphism on calcineurin inhibitors' dose requirements and trough blood levels in stable renal transplant patients.

[2] Influence of CYP3A and ABCB1 polymorphisms on cyclosporine concentrations in renal transplant recipients.

P-glycoprotein, the product of the ABCB1 gene, is an ATP-dependent membrane protein that can transport intracellular xenobiotics out of the cell. P-glycoprotein has a wide range of substrates, and many drugs, such as the immunosuppressant cyclosporine (CsA) and tacrolimus (TAC), are its substrates. rs1128503, rs1045642, and rs2032582 are the most studied SNPs. Their mutations will affect the stability of mRNA and thus the expression and activity of P-gp protein.

rs1128503

A study of 151 Brazilian kidney transplant patients found that the genotype combination rs1128503 TT+rs1045642 The TAC Co/D value of TT+(rs2032582 TT+TA) is significantly higher than that of other genotypes^[1]. In a study of 60 (Spanish) heart transplant patients, it was found that the rs1128503 CC genotype reduced the likelihood of infection and lowered CsA blood concentrations.^[2]. Found in 41 (Spanish) heart transplant patients, rs1045642 rs1128503 The CsA plasma concentration of the rs2032582 (CC/CC/GG) gene mutation type is significantly higher than that of the common type (CT/CT/GT plus TT/TT/TT)^[3]。

References:

[1] Influence of the CYP3A4/5 genetic score and ABCB1 polymorphisms on tacrolimus exposure and renal function in Brazilian kidney transplant patients.

[2] Association of SNPs with the efficacy and safety of immunosuppressant therapy after heart transplantation.

[3] Pharmacogenetic study of ABCB1 and CYP3A5 genes during the first year following heart transplantation regarding tacrolimus or cyclosporine levels.

rs1045642

A study of 46 Brazilian kidney transplant patients found that the rs1045642 TT genotype led to a decrease in the C0/D value of SRL (sirolimus) 15 months after transplantation.^[1]. A study of 151 Brazilian kidney transplants found that the TAC Co/D value of the genotype combination rs1128503 TT+rs1045642 TT+(rs2032582 TT+TA) was significantly higher than that of other genotypes.^[2]. In a study of 63 Chinese Han liver transplant patients, it was found that patients with the rs1045642 CC genotype required higher TAC doses than the other two genotypes.^[3]. A study of 51 lung transplant patients (Spain) found that the rs1045642 CT genotype had significantly higher TAC blood concentrations than the other two genotypes^[4]. Among 41 heart transplant patients, it was found that the CsA blood concentration of rs1045642 rs1128503 rs2032582 (CC/CC/GG) gene mutation was significantly higher than that of the common type (CT/CT/GT+TT/TT/TT).^[5]。

References:

[1] Influence of the CYP3A4/5 genetic score and ABCB1 polymorphisms on tacrolimus exposure and renal function in Brazilian kidney transplant patients.

[2] Influence of the CYP3A4/5 genetic score and ABCB1 polymorphisms on tacrolimus exposure and renal function in Brazilian kidney transplant patients.

[3] Association of MDR1 Gene SNPs and Haplotypes with the Tacrolimus Dose Requirements in Han Chinese Liver Transplant Recipients.

[4] Impact of Single Nucleotide Polymorphisms (SNPs) on Immunosuppressive Therapy in Lung Transplantation.

[5] Pharmacogenetic study of ABCB1 and CYP3A5 genes during the first year following heart transplantation regarding tacrolimus or cyclosporine levels.

rs2032582

A study of 151 Brazilian kidney transplant patients found that the genotype combination rs1128503 TT+rs1045642 The TAC Co/D value of TT+(rs2032582 TT+TA) is significantly higher than that of other genotypes^[1]. Found in 41 (Spanish) heart transplant patients, rs1045642 rs1128503 The CsA plasma concentration of the rs2032582 (CC/CC/GG) gene mutation type is significantly higher than that of the common type (CT/CT/GT+TT/TT/TT)^[2]。

References:

[1] Influence of the CYP3A4/5 genetic score and ABCB1 polymorphisms on tacrolimus exposure and renal function in Brazilian kidney transplant patients.

[2] Pharmacogenetic study of ABCB1 and CYP3A5 genes during the first year following heart transplantation regarding tacrolimus or cyclosporine levels.