Genetic polymorphisms of cytochrome P450 enzymes: CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5 in the Croatian population

Genetic polymorphisms of CYP2C19 in ecuadorian population: An interethnic approach

Introduction

CYP2C19 is a highly polymorphic gene responsible for metabolizing commonly used drugs. CYP2C19*2,*3 (loss of activity alleles) and *17 (increased activity allele) are the principal alleles included in clinical guidelines, however their prevalence varies among different ethnicities. Ecuadorian population is formed by Mestizos, Afrodescendants and Native Americans and frequency of CYP2C19 alleles could be different among them. The objective of this study was to establish the frequency of these variants in the different populations of Ecuador and to compare them with other populations.

Materials and methods

DNA from 105 Afrodescendants, 75 Native Americans of the Kichwa ethnicity, and 33 Mestizos Ecuadorians was analyzed by nested-PCR to identify CYP2C19*17 carriers. CYP2C19*2 allele was analyzed in DNA from 78 Afrodescendants, 29 Native Americans of the Kichwa, and 16 Mestizos by TaqMan Allelic Discrimination Assay. CYP2C19*3 was analyzed in 33 Afrodescendants by nested-PCR.

Results

The global frequencies of the alternate alleles were 14.22% (CYP2C19*2) and 2.10% (CYP2C19*17). No differences (p > 0.05) were observed among the subgroups. No CYP2C19*3 carrier was identified. CYP2C19*2 frequencies in Ecuador were similar to the ones reported in Europe, Africa and Middle East countries and to some American populations. Low CYP2C19*17 frequencies, like the ones in our population, were also observed in East and South Asia and in Native American groups.

Discussion

Absence of differences in the ethnic groups in Ecuador for CYP2C19*2 and *17 could be due to either a bias in sample selection (ethnic group was assed by self-identification) or to a high interethnic admixture in the Ecuadorian population that would had diluted genetic differences. In addition, CYP2C19*2, *3, and *17 alleles frequencies in our study suggest that Ecuadorians ancestry is mostly of Native American origin.

Genetic Diversity of CYP3A5 and ABCB1 Variants in East-Central and South European Populations

BACKGROUND

CYP3A5 enzyme encoded by CYP3A5 is important for drug metabolism in gut and liver, whereas P-glycoprotein by ABCB1, is an ATP-dependent drug efflux pump which exports endo- and exogenous substances outside the cell. Aim: The study was to assess the prevalence of CYP3A5 alleles: *1, *2, *3, *4, *6 and *7, and C and T of ABCB1 in Poles, Belarusians and Bosnians and to compare it with the data reported from other European populations. Subjects and methods: Overall, 511 unrelated healthy subjects from Poland (n = 239), Belarus (n = 104) and Bosnia and Herzegovina (n = 168) were included in this study. Allele frequencies and statistical parameters (AMOVA version 2.9.3) were determined. Results: In Poles, Belarusians and Bosnians the *3 allele of CYP3A5 was the most common, and wild-type allele *1, were: 5.8%, 1.6% and 2.1%, respectively. Allele *2 was very rare, and alleles *4, *6 and *7 were not detected. For the populations mentioned above, the ABCB1 allele C was: 48.1%, 51.4%, 52.4%, respectively.

CONCLUSION

In compared populations, the distribution of CYP3A5 variants but not ABCB1, differed significantly. Alleles *4, *6 and *7 of CYP3A5 did not occur or occurred rarely.

Population pharmacogenomics: an update on ethnogeographic differences and opportunities for precision public health

Both safety and efficacy of medical treatment can vary depending on the ethnogeographic background of the patient. One of the reasons underlying this variability is differences in pharmacogenetic polymorphisms in genes involved in drug disposition, as well as in drug targets. Knowledge and appreciation of these differences is thus essential to optimize population-stratified care. Here, we provide an extensive updated analysis of population pharmacogenomics in ten pharmacokinetic genes (CYP2D6, CYP2C19, DPYD, TPMT, NUDT15 and SLC22A1), drug targets (CFTR) and genes involved in drug hypersensitivity (HLA-A, HLA-B) or drug-induced acute hemolytic anemia (G6PD). Combined, polymorphisms in the analyzed genes affect the pharmacology, efficacy or safety of 141 different drugs and therapeutic regimens. The data reveal pronounced differences in the genetic landscape, complexity and variant frequencies between ethnogeographic groups. Reduced function alleles of CYP2D6, SLC22A1 and CFTR were most prevalent in individuals of European descent, whereas DPYD and TPMT deficiencies were most common in Sub-Saharan Africa. Oceanian populations showed the highest frequencies of CYP2C19 loss-of-function alleles while their inferred CYP2D6 activity was among the highest worldwide. Frequencies of HLA-B*15:02 and HLA-B*58:01 were highest across Asia, which has important implications for the risk of severe cutaneous adverse reactions upon treatment with carbamazepine and allopurinol. G6PD deficiencies were most frequent in Africa, the Middle East and Southeast Asia with pronounced differences in variant composition. These variability data provide an important resource to inform cost-effectiveness modeling and guide population-specific genotyping strategies with the goal of optimizing the implementation of precision public health.

Loss of function polymorphisms in SLCO1B1 (c.521T>C, rs4149056) and ABCG2 (c.421C>A, rs2231142) genes are associated with adverse events of rosuvastatin: a case-control study

PURPOSE

The study aims to evaluate relationship between polymorphisms associated with a reduced function of two transporter proteins resulting in increased exposure to rosuvastatin - organic anion transporter 1B1 (OATP1B1) (SLCO1B1 c.521T>C) and ATP binding cassette subfamily G member 2 (ABCG2) (ABCG2 c.421C>A) and occurrence of rosuvastatin related myotoxicity/hepatotoxicity.

METHODS

In a case-control study, cases (rosuvastatin treated patients developing myotoxicity or hepatotoxicity) and controls (concurrent rosuvastatin treated patients free of adverse events) were prospectively recruited over a 2 year period in a single tertiary center specialized in treatment of metabolic disorders. Subjects were evaluated for clinical, comorbidity, and comedication characteristics and for genotype predicted metabolizing phenotypes regarding cytochrome P450 enzymes CYP2C9 and CYP2C19. Standard regression analysis and analysis in matched sets of cases and controls (optimal full matching) were undertaken by fitting frequentist and Bayesian models (covariates/matching variables: age, sex, diabetes, liver/renal disease, hypertension, CYP2C9 and C19 phenotype, use of CYP or transporter inhibitors, non evaluated transporter genotype).

RESULTS

A total of 88 cases (81 with myotoxicity, 6 with hepatotoxicity, 1 with both) and 129 controls were recruited. Odds of variant SLCO1B1 c.521T>C allele were 2.2-2.5 times higher in cases than in controls (OR = 2.45, 95% CI 1.34-4.48; Bayesian OR = 2.59, 95% CrI 1.42-4.90 in regression analysis; OR = 2.20, 1.10-4.42; Bayesian OR = 2.26, 1.28-4.41 in matched analysis). Odds of variant ABCG2 c.421C>A allele were 2.1-2.3 times higher in cases than in controls (OR = 2.24, 1.04-4.83; Bayesian OR = 2.35, 1.09-4.31 in regression analysis; OR = 2.10, 0.83-5.31; Bayesian OR = 2.17, 1.07-4.35 in matched analysis).

CONCLUSION

Loss of function polymorphisms in SLCO1B1 c.521T>C and ABCG2 c.421C>A genes are associated with the presence of rosuvastatin related myotoxicity and/or hepatotoxicity.

Prevalence of five pharmacologically most important CYP2C9 and CYP2C19 allelic variants in the population from the Republic of Srpska in Bosnia and Herzegovina

The enzymes of the cytochrome P450 superfamily play a critical role in phase I drug metabolism. Among them, CYP2C9 and CYP2C19 are clinically important, as they can mediate severe toxicity, therapy failure, and increased susceptibility to cancer and other diseases caused by chemicals. The aim of this study was to determine the prevalence of pharmacologically most important allelic variants of the CYP2C9 and CYP2C19 genes in the general population of the Republic of Srpska (Bosnia and Herzegovina) and to compare them with other populations. For this purpose we determined the genotype profile and allele frequency of 216 randomly selected healthy volunteers using real-time polymerase chain reaction (RT-PCR). The prevalence of the CYP2C9 *2 and *3 alleles was 13.6 and 7.4 %, respectively. Based on these frequencies, of the 216 participants four (1.86 %) were predicted to be poor metabolisers, 78 (36.11 %) intermediate, and the remaining 134 (62.03 %) normal metabolisers. Based on the prevalence of CYP2C19 *2 and *17 variants – 16.2 and 20.4 %, respectively – nine (4.17 %) were predicted to be poor, 57 (26.39 %) rapid, and nine (4.17 %) ultra-rapid metabolisers. We found no significant differences in allele frequencies in our population and populations from other European countries. These findings suggest that genetically determined phenotypes of CYP2C9 and CYP2C19 should be taken into consideration to minimise individual risk and improve benefits of drug therapy in the Republic of Srpska.

Different Pharmacokinetics of Tramadol, O-Demethyltramadol and N-Demethyltramadol in Postoperative Surgical Patients From Those Observed in Medical Patients

Background: Most studies examining tramadol metabolism have been carried out in non-surgical patients and with oral tramadol. The aim of this study was 1) to measure concentrations of tramadol, O-demethyltramadol (ODT), and N-demethyltramadol (NDT) in the surgical patients admitted to the intensive care unit (ICU) within the first 24 postoperative hours after intravenous application of tramadol, and 2) to examine the effect of systemic inflammation on tramadol metabolism and postoperative pain. Methods: A prospective observational study was carried out in the surgical ICU in the tertiary hospital. In the group of 47 subsequent patients undergoing major abdominal surgery, pre-operative blood samples were taken for CYP2D6 polymorphism analysis. Systemic inflammation was assessed based on laboratory and clinical indicators. All patients received 100 mg of tramadol intravenously every 6 h during the first postoperative day. Postoperative pain was assessed before and 30 min after tramadol injections. Tramadol, ODT, and NDT concentrations were determined by high-performance liquid chromatography. Results: CYP2D6 analysis revealed 2 poor (PM), 22 intermediate (IM), 22 extensive (EM), and 1 ultrafast metabolizer. After a dose of 100 mg of tramadol, t1/2 of 4.8 (3.2-7.6) h was observed. There were no differences in tramadol concentration among metabolic phenotypes. The area under the concentration-time curve at the first dose interval (AUC1-6) of tramadol was 1,200 (917.9-1944.4) μg ×h ×L-1. NDT concentrations in UM were below the limit of quantification until the second dose of tramadol was administrated, while PM had higher NDT concentrations compared to EM and IM. ODT concentrations were higher in EM, compared to IM and PM. ODT AUC1-6 was 229.6 (137.7-326.2) μg ×h ×L-1 and 95.5 (49.1-204.3) μg ×h ×L-1 in EM and IM, respectively (p = 0.004). Preoperative cholinesterase activity (ChE) of ≤4244 U L-1 was a cut-off value for a prediction of systemic inflammation in an early postoperative period. NDT AUC1-6 were significantly higher in patients with low ChE compared with normal ChE patients (p = 0.006). Pain measurements have confirmed that sufficient pain control was achieved in all patients after the second tramadol dose, except in the PM. Conclusions: CYP2D6 polymorphism is a major factor in O-demethylation, while systemic inflammation accompanied by low ChE has an important role in the N-demethylation of tramadol in postoperative patients. Concentrations of tramadol, ODT, and NDT are lower in surgical patients than previously reported in non-surgical patients. Clinical Trial Registration: ClinicalTrials.gov, NCT04004481.

CYP2D6 and CYP3A4 variants influence the risk and outcome of COVID-19 infection among rheumatoid arthritis patients maintained on hydroxychloroquine

OBJECTIVES

Hydroxychloroquine (HCQ) has been used as an off label for the management of coronavirus disease (Covid-19) infection with other drugs. However, different genetic variants can affect the metabolism of HCQ leading to inter-individual differences in its efficacy. In this study, we investigated the effects of variants in CYP2D6, CYP3A4 and CYP3A5 on the risk of Covid-19 infection among patients receiving HCQ for controlling rheumatoid arthritis (RA).

METHODS

A total of 60 patients were genotyped for CYP2D6*2XN, CYP2D6*4, CYP3A4*1B and CYP3A5*2. They were receiving HCQ for the treatment of RA. The patients were evaluated clinically for fever and dry cough, radiologically via chest computed tomography (CT) and immunologically via anti-Covid-19 IgG and IgM titers.

RESULTS

Variants in CYP2D6 significantly affected the grade of ground glass (CYP2D6*4 AA carriers showed the higher risk for grade 3) and the risk of positive anti-Covid-19 IgM (CYP2D6*2XN CC and CYP3A4*1B AA had the lowest risk), the duration of HCQ, the use of corticosteroids or gender did not affect the Covid-19 status significantly.

CONCLUSIONS

In general, the outcome of the studied patients receiving HCQ was good (no deaths, no intubation needed). CYP2D6 variants could affect the outcome of Covid-19 infection.

Influence of CYP3A polymorphisms on tacrolimus pharmacokinetics in kidney transplant recipients

Tacrolimus is characterized by a highly variable pharmacokinetics (PK) and a small therapeutic window. It is metabolized specifically by the CYP3A isoenzymes. This study aimed to determine, in kidney transplant patients, the influence of different genotypic clusters involving these SNPs CYP3A4*1B, CYP3A4*22, and CYP3A5*3 on Tacrolimus bioavailability during the first (PTP1) and the second (PTP2) posttransplant phase (PT). We included kidney transplant patients who received Tacrolimus and underwent drug monitoring by C0 monitoring. CYP3A4 and CYP3A5 genotyping were performed using PCR-RFLP. We classified the patients into four groups: Slow, Intermediate, rapid, and ultra-rapid metabolizers. We included 80 patients. The Tacrolimus dose-normalized C0 (C0/D ratio) was significantly decreased in intermediate, rapid, and ultra-rapid comparing with slow metabolisers. During PTP1 only CYP3A5*3 and CYP3A4*22 polymorphisms correlate significantly with C0/D ratio. Regardless of the PT phase and during the late one, only the CYP3A4 polymorphisms correlate significantly with the C0/D ratio. We identified that these SNPs are all associated independently with Tacrolimus exposure in different PT phases. Moreover, we are the first to define a genotypic cluster including the three CYP3A SNPs.

Clinical Relevance of CYP2D6 Polymorphisms in Patients of an Austrian Medical Practice: A Family Practice-Based Observational Study

BACKGROUND

Around 20-30% of all prescribed drugs are estimated to be metabolised by the cytochrome P450 (CYP) 2D6 enzyme. In a medical practice, it is usually not known whether a patient is a poor, intermediate, normal or ultra-rapid metaboliser for CYP2D6-metabolised drugs.

OBJECTIVE

This study aims to explore the clinical relevance and the extent of hazardous prescriptions by analysing the metaboliser status of patients already taking such drugs.

METHODS

This is a family practice-based observational study performed in a rural practice for general and family medicine in Lower Austria providing care for approximately 2100 patients annually. In 287 consecutive patients, who had taken or were taking a drug metabolised by CYP2D6 during the last 3 years, the metaboliser status was analysed.

RESULTS

The genetic analysis of 287 patients resulted in 51.22% normal metabolisers, 38.68% intermediate metabolisers, 6.27% poor metabolisers and 3.83% ultra-rapid metabolisers. In 50 cases (poor metaboliser, intermediate metaboliser and ultra-rapid metaboliser, i.e. 17.42% of all tested patients taking a CYP2D6-specific drug), an altered gene function was identified, for which clinical guideline annotations, drug label annotations, or clinical annotations are available. Allele and genotype frequencies were in accordance with data from other European studies.

CONCLUSIONS

In 17.42% of all patients already taking a drug metabolised by CYP2D6, knowledge of the genetically defined metaboliser status would have been of immediate clinical relevance before prescribing the drug. CLINICALTRIALS.

GOV IDENTIFIER

NCT03859622.

Defining screening panel of functional variants of CYP1A1, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 genes in Serbian population

Plethora of drugs and toxic substances is metabolized by cytochrome P450 enzymes (CYP450). These enzymes are coded by highly variable genes abundant with single nucleotide variants (SNVs) and small insertions/deletions (indels) that affect the functionality of the enzymes, increasing or decreasing their activity. CYP genes genotyping, followed by haplotype inference, provides substrate specific metabolic phenotype prediction. This is crucial in pharmacogenetics and applicable in molecular autopsy. However, high number of alleles in CYP450 superfamily and interethnic variability in frequency distribution require precise gene panel customization. To estimate informativeness of SNVs and alleles in CYP gene families 1, 2, and 3, associated with metabolic alterations, 500 unrelated individuals from 5 regions of Serbia were genotyped using TaqMan assays to determine frequencies of CYP2C9 *2 and *3, CYP2C19 *2 and *17 alleles, four variants in CYP2D6 (rs3892097, rs1065852, rs28371725, rs28371706) gene, and CYP3A4*1B allele. In addition, CYP1A1 rs4646903 and rs1048943 (m1 and m2) variants were genotyped by RFLP. Our results showed that frequencies of tested variants in Serbian population corresponded to general European population and somewhat differed from neighboring populations. SNV rs1065852, the main contributor to non-functional CYP2D6 *4, significantly departed from Hardy-Weinberg equilibrium. With the exception of rs28371706 in CYP2D6 and rs2740574 in CYP3A4, which were very rare in our sample, all other tested variants in CYP2 family are informative and appropriate for pharmacogenetic testing, molecular autopsy, and medico-legal genetic analyses.

High-Resolution Melting Assay for Genotyping Variants of the CYP2C19 Enzyme and Predicting Voriconazole Effectiveness

Voriconazole is a triazole antifungal agent recommended as primary treatment for invasive aspergillosis, as well as some other mold infections. However, it presents some pharmacokinetic singularities that lead to a great variability intra- and interindividually, nonlinear pharmacokinetics, and a narrow therapeutic range. Most experts have recommended tracing the levels of voriconazole in patients when receiving treatment. This azole is metabolized through the hepatic enzyme complex cytochrome P450 (CYPP450), with the isoenzyme CYP2C19 being principally involved. Allelic variations (polymorphisms) of the gene that encodes this enzyme are known to contribute to variability in voriconazole exposure. Three different allelic variants, CYP2C19*17, CYP2C19*2, and CYP2C19*3, could explain most of the phenotypes related to the voriconazole metabolism and some of its pharmacokinetic singularities. We designed a rapid molecular method based on high-resolution melting to characterize these polymorphisms in a total of 142 samples, avoiding sequencing. Three PCRs were designed with similar cycling conditions to run simultaneously. The results showed that our method represents a fast, accurate, and inexpensive means to study these variants related to voriconazole metabolism. In clinical practice, this could offer a useful tool to individually optimize therapy and reduce expenses in patients with fungal infections.

Interaction between ABCG2 421C>A polymorphism and valproate in their effects on steady-state disposition of lamotrigine in adults with epilepsy

AIMS

To investigate the impact of glucuronidation enzyme (UGT1A4*3 142T>G, UGT1A4*2 70C>A, UGT2B7 -161C>T) and transporter (MDR1/ABCB1 1236C>T, ABCG2 421C>A) polymorphisms on steady-state disposition of lamotrigine and on the lamotrigine-valproate interaction.

METHODS

Adults with epilepsy on lamotrigine monotherapy (n = 131) or lamotrigine + valproate treatment (n = 74) were genotyped and steady-state lamotrigine and valproate morning troughs were determined as a part of routine therapeutic drug monitoring.

RESULTS

No effect of UGT and MDR1/ABCB1 polymorphisms was observed. In the entire cohort, ABCG2 421A allele had no effect however an interaction between the variant allele and valproate was observed: (i) in lamotrigine-only patients, variant allele (vs. wild type homozygosity) was independently (adjustments: age, sex, body mass index, lamotrigine dose, other polymorphisms) associated with mildly lower lamotrigine troughs [geometric means ratio (GMR) = 0.76, 95% confidence interval (CI) 0.59-0.98], whereas in lamotrigine + valproate patients it was associated with higher troughs (GMR = 1.72, 95%CI 1.14-2.62); (ii) valproate cotreatment was overall associated with markedly higher troughs vs. lamotrigine monotherapy (GMR = 3.49, 95%CI 2.73-4.44), but more so in variant allele carriers (GMR = 5.24, 95%CI 3.38-8.15) than in wild type homozygotes (GMR = 2.32, 95%CI 1.89-2.83); (iii) variant allele effects in two treatment subsets and valproate effects in two genotype subsets differed by 2.36-fold (95%CI 1.39-3.67); (iv) increase in lamotrigine troughs associated with increasing valproate troughs was greater in variant allele carriers than in wild type homozygotes, i.e. variant allele effect increased with increasing valproate troughs.

CONCLUSION

This study is first to indicate a potentially relevant interaction between ABCG2 421C>A polymorphism and valproate in their effects on lamotrigine disposition.

Genetic polymorphisms of CYP2C9, CYP2C19, and CYP3A5 in Kosovar population

Cytochrome P450 genetic polymorphisms are responsible for individual variations in drug metabolism and drug-drug interactions. They are very important for pharmacogenetics, and their frequency varies across different populations. There is a big gap in the knowledge about the CYP gene family polymorphisms in the population of Kosovo, and the aim of our study was to fill that gap by determining the frequency of the most important variant alleles of CYP2C9, CYP2C19, and CYP3A5 in 234 nonrelated Kosovars. The allele frequencies of CYP2C9*2 and 2C9*3 were 17.52 %, and 10.89 %, respectively. Sixteen participants (6.81 %) were CYP2C9 poor metabolisers. The CYP2C19*2 and *17 variant frequencies were 13.03 % and 19.01 %, respectively. There were 2.13 % CYP2C19 poor and 4.27 % ultra-rapid metabolisers (homozygous carriers of the *17 allele). With regard to CYP3A5, the frequency of the *3 variant allele was 98.29 % (non-expressors), while the remaining participants (1.70 %) were expressors of CYP3A5. These findings are comparable with other European ethnicities, specifically those of Southeast Europe.

Association between CYP2C19*2 variant and clinical outcome in Clopidogrel treated patients from Republic of Macedonia

Clopidogrel is the thienopyridine of choice for prevention of ischemic events and stent thrombosis in patients with atherotrombotic disease. Recent studies suggest that certain genetic variants involving CYP450 system are responsible for wide interindividual variability in treatment response profiles among clopidogrel treated individuals. The aim of this study was to define the prevalence of most common CYP2C19*2: 681G>A (rs4244285) allelic variant in Macedonian population and determine the risk association with major cardiovascular adverse events in clopidogrel treated patients with atherotrombotic cardiovascular disease. CYP2C19 *2 genotype was assessed in 198 subjects from R.Macedonia. The association between the reduced function CYP2C19 *2 A allele and clinical outcome was evaluated in 67 clopidogrel treated patients within a follow up period of at least 6 months (from 6 to 60 months) after initializing clopidogrel therapy. The population frequency of polymorphic A allele responsible for impaired clopidogrel metabolism in Macedonian population was 0.18. CYP2C19*2 variant was significantly associated with increased rate of adverse cardiovascular events in the allelic (OR= 3.188; 95% CI= 1.437-7.058), dominant (OR=3.477; 95% CI= 1.256-9.630) and co-dominant model ( OR=6.750, 95% CI: 1.186-38.410) of statistical analysis (adjusted OR= 2.619; Ptrend=0.0088). The influence of CYP2C19*2 was most strongly correlated with worse event free survival in patients carrying AA genotype (log rank P = 0.0024) and patients carrying at least one CYP2C19*2 reduced function allele (log rank P=0.0058). CYP2C19*2 genetic variant in the population from Republic of Macedonia has similar distribution as determined in other European populations. Carriage of reduced function CYP2C19 *2 allele is associated with worse event free survival in clopidogrel treated patients with atherotrombotic disorders.