Identification of a null allele of cytochrome P450 3A7: CYP3A7 polymorphism in a Korean population

Allele and genotype frequencies of CYP3A4, CYP3A5, CYP3A7, and GSTP1 gene polymorphisms among mainland Tibetan, Mongolian, Uyghur, and Han Chinese populations

Over 50% prescribed drugs are metabolised by cytochrome P450 3A (CYP3A) and glutathione S-transferase pi (GSTP1) adds a glutathione to the oxidative products by CYP3A, which increases the hydrophilic property of metabolites and facilitates the excretion. Single nucleotide polymorphisms (SNPs) of CYP3A and GSTP1 show a diverse allele and genotype frequencies distribution among the world populations. The present study aimed to investigate the genotype and allele frequency distribution patterns of CYP3A4, CYP3A5, CYP3A7 and GSTP1 polymorphisms among healthy participants in mainland Tibetan, Mongolian, Uyghur, and Han Chinese populations. Blood samples were collected from 842 unrelated healthy subjects (323 Tibetan, 134 Mongolian, 162 Uyghur, and 223 Han) for genotyping analysis. Variant allele frequencies of CYP3A4 rs2242480, CYP3A5 rs776746, CYP3A7 rs2257401, and GSTP1 Ile105Val were observed in Han (0.253, 0.686, 0.312 and 0.188), Tibetan (0.186, 0.819, 0.192 and 0.173), Mongolian (0.198, 0.784, 0.228 and 0.235) and Uyghur (0.179, 0.858, 0.182 and 0.250) respectively. The allele frequency of CYP3A7*1C in Uyghur (0.019) was higher than that in Tibetan (0.002, p < 0.01). There was a strong linkage disequilibrium between CYP3A4 rs2242480, CYP3A5 rs776746, and CYP3A7 rs2257401 among the four ethnic groups. The results might be useful for the precise medication in the Chinese populations.

OpenCYP: An open source database exploring human variability in activities and frequencies of polymophisms for major cytochrome P-450 isoforms across world populations

The open source database "OpenCYP database" has been developed based on the results of extensive literature searches from the peer-reviewed literature. OpenCYP provides data on human variability on baseline of activities and polymophism frequencies for selected cytochrome P-450 isoforms (CYP1A2, CYP2A6, CYP2D6, CYP3A4/3A5 and CYP3A7) in healthy adult populations from world populations. CYP enzymatic activities were generally expressed as the metabolic ratio (MR) between an unchanged probe drug and its metabolite(s) in urine or plasma measured in healthy adults. Data on other age groups were very limited and fragmented, constituting an important data gap. Quantitative comparisons were often hampered by the different experimental conditions used. However, variability was quite limited for CYP1A2, using caffeine as a probe substrate, with a symmetrical distribution of metabolic activity values. For CYP3A4, human variability was dependent on the probe substrate itself with low variability when data considering the dextromethorphan/demethilathed metabolite MR were used and large variability when the urinary 6β-hydroxycortisol/cortisol ratio was used. The largest variability in CYP activity was shown for CYP2D6 activity, after oral dosing of dextromethorphan, for which genetic polymorphisms are well characterised and constitute a significant source of variability. It is foreseen that the OpenCYP database can contribute to promising tools to support the further development of QIVIVE and PBK models for human risk assessment of chemicals particularly when combined with information on isoform-specific content in cells using proteomic approaches.

Neonatal cytochrome P450 CYP3A7: A comprehensive review of its role in development, disease, and xenobiotic metabolism

The human cytochrome P450 CYP3A7, once thought to be an enzyme exclusive to fetal livers, has more recently been identified in neonates and developing infants as old as 24 months post-gestational age. CYP3A7 has been demonstrated to metabolize two endogenous compounds that are known to be important in the growth and development of the fetus and neonate, namely dehydroepiandrosterone sulfate (DHEA-S) and all-trans retinoic acid (atRA). In addition, it is also known to metabolize a variety of drugs and xenobiotics, albeit generally to a lesser extent relative to CYP3A4/5. CYP3A7 is an important component in the development and protection of the fetal liver and additionally plays a role in certain disease states, such as cancer and adrenal hyperplasia. Ultimately, a full understanding of the expression, regulation, and metabolic properties of CYP3A7 is needed to provide neonates with appropriate individualized pharmacotherapy. This article summarizes the current state of knowledge of CYP3A7, including its discovery, distribution, alleles, RNA splicing, expression and regulation, metabolic properties, substrates, and inhibitors.

Whole exome sequencing for the identification of CYP3A7 variants associated with tacrolimus concentrations in kidney transplant patients

The purpose of this study was to identify genotypes associated with dose-adjusted tacrolimus trough concentrations (C₀/D) in kidney transplant recipients using whole-exome sequencing (WES). This study included 147 patients administered tacrolimus, including seventy-five patients in the discovery set and seventy-two patients in the replication set. The patient genomes in the discovery set were sequenced using WES. Also, known tacrolimus pharmacokinetics-related intron variants were genotyped. Tacrolimus C₀/D was log-transformed. Sixteen variants were identified including novel CYP3A7 rs12360 and rs10211 by ANOVA. CYP3A7 rs2257401 was found to be the most significant variant among the periods by ANOVA. Seven variants including CYP3A7 rs2257401, rs12360, and rs10211 were analyzed by SNaPshot in the replication set and the effects on tacrolimus C₀/D were verified. A linear mixed model (LMM) was further performed to account for the effects of the variants and clinical factors. The combined set LMM showed that only CYP3A7 rs2257401 was associated with tacrolimus C₀/D after adjusting for patient age, albumin, and creatinine. The CYP3A7 rs2257401 genotype variant showed a significant difference on the tacrolimus C₀/D in those expressing CYP3A5, showing its own effect. The results suggest that CYP3A7 rs2257401 may serve as a significant genetic marker for tacrolimus pharmacokinetics in kidney transplantation.

Influence of CYP3A and ABCB1 polymorphisms on cyclosporine concentrations in renal transplant recipients

Aim: Cyclosporine is a substrate of CYP3A and ABCB1. This study examined the role of CYP3A and ABCB1 polymorphisms on cyclosporine pharmacokinetics in renal transplant recipients. Patients & methods: CYP3A and ABCB1 SNPs were detected in 521 recipients. The relationships of dose-adjusted concentrations with corresponding genotypes were investigated at the different terms. Results: CYP3A5 rs776746 and CYP3A7 rs10211 genotype affect C0/D at the short-term, medium-term and long-term after transplantation (p < 0.05). CYP3A7 rs2257401 genotype affects C2/D at the medium-term (p < 0.05). CYP3A4 rs4646437, CYP3A5 rs776746 and CYP3A7 rs2257401 genotype affect C2/D at the long-term (p < 0.05). There are no relationships between ABCB1 polymorphism and cyclosporine C/D. Conclusion: CYP3A genetic factors (rs776746, rs4646437, rs2257401 and rs10211) were varied in different stages after transplantation. The role of CYP3A7 in cyclosporine metabolism requires further study.

Association of IL-10-1082 G/G genotype with lower mortality of acute respiratory distress syndrome in a Chinese population

We aimed to investigate whether interleukin-10 (IL-10) -1082 G/G genotype is associated with lower mortality of acute respiratory distress syndrome (ARDS) in a Chinese population. A hospital-based case-control study was conducted in 314 cases of ARDS and 210 controls who were admitted to an intensive care unit with sepsis, trauma, aspiration or massive transfusions. Cases were followed for 30-day mortality. The -1082G/G genotype was associated with lower development of ARDS (OR=0.51; 95% CI 0.34-0.76; P=0.001). Among patients with ARDS, the -1082G/G genotype was associated with lower 30-day mortality (OR=0.44; 95% CI 0.25-0.76; P=0.003). In conclusion, IL-10-1082 G/G genotype is associated with lower development and mortality of ARDS in a Chinese population.