Analysis of single-nucleotide polymorphisms (SNPs) in human CYP3A4 and CYP3A5 genes: potential implications for the metabolism of HIV drugs

Abstract

BackgroundDrug metabolism via the cytochrome P450 (CYP450) system has emerged as an important determinant in the occurrence of several drug interactions (adverse drug reactions, reduced pharmacological effect, drug toxicities). In particular, CYP3A4 and CYP3A5 (interacting with more than 60% of licensed drugs) exhibit the most individual variations of gene expression, mostly caused by single nucleotide polymorphisms (SNPs) within the regulatory region of the CYP3A4 and CYP3A5 genes which might affect the level of enzyme production.In this study, we sought to improve the performance of sensitive screening for CYP3A polymorphism detection in twenty HIV-1 infected patients undergoing lopinavir/ritonavir (LPV/r) monotherapy.MethodsThe study was performed by an effective, easy and inexpensive home-made Polymerase Chain Reaction Direct Sequencing approach for analyzing CYP3A4 and CYP3A5 genes which can detect both reported and unreported genetic variants potentially associated with altered or decreased functions of CYP3A4 and CYP3A5 proteins. Proportions and tests of association were used.ResultsAmong the genetic variants considered, CYP3A4*1B (expression of altered function) was only found in 3 patients (15%) and CYP3A5*3 (expression of splicing defect) in 3 other patients (15%). CYP3A5*3 did not appear to be associated with decreased efficacy of LPV/r in any patient, since none of the patients carrying this variant showed virological rebound during LPV/r treatment or low levels of TDM. In contrast, low-level virological rebound was observed in one patient and a low TDM level was found in another; both were carrying CYP3A4*1B.ConclusionsOur method exhibited an overall efficiency of 100% (DNA amplification and sequencing in our group of patients). This may contribute to producing innovative results for better understanding the inter-genotypic variability in gene coding for CYP3A, and investigating SNPs as biological markers of individual response to drugs requiring metabolism via the cytochrome P450 system.

Potential implications of CYP3A4, CYP3A5 and MDR‐1 genetic variants on the efficacy of Lopinavir/Ritonavir (LPV/r) monotherapy in HIV‐1 patients

“…The aim of this study was: (i) to develop an in-house PCR/direct sequencing, based on DNA purification of full-length CYP3A4 and CYP3A5 genes (SNPs) and MDR1 C3435T variant; (ii) to investigate association of CYP3A4 and CYP3A5 reported or unreported genetic polymorphisms and MDR1-C3435T (CC homozygote, CT heterozygote, TT homozygote) with clinical outcome of HIV-1 infected subjects treated with PI. Methods: Overall, 39 HIV-1 infected patients receiving boosted Lopinavir (LPV/r) monotherapy after virological suppression were genotyped and analyzed through PCR and direct sequencing of full-length CYP3A4 and CYP3A5 gene sequences [1] and MDR1 gene (C3435T). CD4'T-cell counts and plasma viral load were analyzed before and after LPV/r initiation; LPV/r therapeutic drug monitoring (TDM) was determined at 12-hours.…”

Population Approach To Analyze the Pharmacokinetics of Free and Total Lopinavir in HIV-Infected Pregnant Women and Consequences for Dose Adjustment

“…DNAs were extracted (n ϭ 100) using a blood midikit (Qiagen SA, Courtaboeuf, France) according to the manufacturer's instructions. Based on a review of the literature, we selected several single nucleotide polymorphisms (SNP) with known functional impacts on LPV metabolism: CYP3A5 gene (rs776746 polymorphism), CYP3A4 (rs2242480), P-gp (rs1045642 and rs2032582), and SLCO1B1 (rs4149056) (10,(25)(26)(27)(28). Five predesigned TaqMan allelic discrimination primers and probes were purchased from Applied Biosystems (Foster City, CA).…”

Deleterious Nonsynonymous SNP Found within <i>HLA-DRB1</i> Gene Involved in Allograft Rejection in Sudanese Family: Using DNA Sequencing and Bioinformatics Methods

“…Single nucleotide polymorphisms (SNPs) are variations of a single base, either between two homologous chromosomes within a single individual, or between two individuals [9]. Genetic polymorphisms are wellrecognized sources of individual differences in disease risk and treatment response [10]. While the majority of SNPs have no biological consequences, a fraction of gene substitutions have functional significance and provide the basis for the diversity found among humans [10].…”

“…Genetic polymorphisms are wellrecognized sources of individual differences in disease risk and treatment response [10]. While the majority of SNPs have no biological consequences, a fraction of gene substitutions have functional significance and provide the basis for the diversity found among humans [10]. However, during the last decade, single nucleotide polymorphisms (SNPs) have become increasingly used because of their abundance in the genome, ease of replication in different laboratories and simplicity of analysis [11].…”