Allele and genotype frequencies of the polymorphic cytochrome P450 genes (CYP1A1, CYP3A4, CYP3A5, CYP2C9 and CYP2C19) in the Jordanian 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 variation of CYP2C9 gene and its correlation with cardiovascular disease risk factors

BACKGROUND

The major enzyme that is responsible for Sulfonylureas (SUs) metabolism is hepatic cytochrome P-450 2C9 (CYP2C9). It is encoded by the polymorphic gene CYP2C9, which has many allelic variants, among those the CYP2C9*2 and CYP2C9*3 are the most common and clinically significant allelic variations. People with diabetes mellitus type 2 (T2DM) are more likely to develop cardiovascular disease (CVD), and their risk of dying from it is more than two times higher than that of people without the condition. The purpose of this study was to evaluate the association of genetic variations in the CYP2C9 gene with cardiovascular risk factors by investigating CYP2C9*1, *2, *3, *5, *11, and *13 allelic variants.

METHODS AND RESULTS

A total of 226 participants were enrolled in the current case-control study. Allele-specific amplification- PCR (ASA-PCR) was used to determine the allele of different variations and the results were confirmed by sequencing. The findings of this study showed the presence of the CYP2C9*2 allele in the T2DM group does not differ from its percentage in the control group. Also, CYP2C9*3 allele frequencies identified by Hardy-Weinberg equilibrium (HWE) analysis law were not significant, p = 0.6593 and 0.5828 in T2DM and control groups. There is no statistically significant difference between the control and diabetes groups involving the distribution of CYP2C9 alleles and CYP2C9*5, *11, and *13 polymorphisms were absent in the Iraqi population. No carrier for the CYP2C9*3 homozygous state was found in both groups.

CONCLUSIONS

According to these results T2DM patients with the CYP2C9*2 and *3 variants have an increased risk of developing hypertension.

The potential implication of MDR1 and NAC1 genetic polymorphisms on resistance to antiepileptic drugs among a Jordanian epileptic population: a cross-sectional study

BACKGROUND

Resistance to antiepileptic drugs (AEDs) remains one of the main challenges to neurologists. Polymorphisms of drug efflux transporters such as multidrug resistance (MDR1) gene and target sites such as the nucleus accumbens-associated 1 (NAC1) gene have been suggested to influence the responsiveness to treatment.

AIM

Evaluation of the association of MDR1 and NAC1 polymorphisms with AEDs resistance among Jordanian epileptic patients.

SUBJECTS AND METHODS

86 Jordanian epileptics were included in the study. DNA was extracted and genotyping was conducted by polymerase chain reaction followed by sequencing. Nine single nucleotide polymorphisms (SNPs) on the MDR1 gene and six SNPs on the NAC1 gene were investigated.

RESULTS

MDR1 and NAC1 polymorphisms don't seem to influence the resistance to AEDs at the genotype or allele level. However, a strong association was found between MDR1 rs2032588 (OR = 5; 95%CI = [1.3-18.8], p = 0.01) and AEDs resistance among males at the allele level. Also, data revealed an association between MDR1 rs1128503 and AEDs resistance among females at the allele level.

CONCLUSION

The data suggest that MDR1 and NAC1 polymorphisms do not influence the AEDs resistance among Jordanian epileptics. However, there is a gender-dependent association between MDR1 polymorphisms and resistance to AEDs at two SNPs (rs2032588 and rs1128503).

Ethnicity-based classifications and medical genetics: One Health approaches from a Western Pacific perspective

A new era presently dawns for medical genetics featuring individualised whole genome sequencing and promising personalised medical genetics. Accordingly, we direct readers attention to the continuing value of allele frequency data from Genome-Wide Association Surveys (GWAS) and single gene surveys in well-defined ethnic populations as a guide for best practice in diagnosis, therapy, and prescription. Supporting evidence is drawn from our experiences working with Austronesian volunteer subjects across the Western Pacific. In general, these studies show that their gene pool has been shaped by natural selection and become highly diverged from those of Europeans and Asians. These uniquely evolved patterns of genetic variation underlie contrasting schedules of disease incidence and drug response. Thus, recognition of historical bonds of kinship among Austronesian population groups across the Asia Pacific has distinct public health advantages from a One Health perspective. Other than diseases that are common among them like gout and diabetes, Austronesian populations face a wide range of climate-dependent infectious diseases including vector-borne pathogens as they are now scattered across the Pacific and Indian Oceans. However, we caution that the value of genetic survey data in Austronesians (and other groups too) is critically dependent on the accuracy of attached descriptive information in associated metadata, including ethnicity and admixture.

Genetic variation of pharmacogenomic VIP variants in the Chinese Li population: an updated research

Previous studies have shown that the frequency of very important pharmacogenomic (VIP) genes varies in different populations which leads to the diversities in drug efficacy, safety, and the risk associated with adverse drug reactions (ADRs). The purpose of this study was to identify the distribution differences of VIP variants between the Li population and the other 13 populations. Based on the Pharmacogenomics Knowledgebase database (PhamGKB), we successfully genotyped 52 VIP variants within 27 genes in 200 unrelated Li population. χ² test was used to evaluate the significant differences of genotype and allele frequencies between the Li and the other 13 populations from 1000 Genomes Project. Our study showed that the genotype frequencies of single nucleotide polymorphisms (SNPs) on KCNH2, ACE, CYP4F2, and CYP2E1 were considerably different between Li and the other 13 populations, especially in rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) loci. Meanwhile, we found several VIP variants that might alter the drug metabolism of cisplatin-cyclophosphamide (CYP2E1), vitamin E (CYP4F2), asthma amlodipine, chlorthalidone, and lisinopril (ACE) through PharmGKB. We also identified other variants which were associated with adverse effects in isoniazid and rifampicin (CYP2E1; hepatotoxicity). The four loci rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) provided a reliable basis for the prediction of the efficacy of certain drugs. The study complemented the existed pharmacogenomics information, which could provide theoretical basis for predicting the efficacy of certain drugs in the Li population.

Genophenotypic Factors and Pharmacogenomics in Adverse Drug Reactions

Adverse drug reactions (ADRs) rank as one of the top 10 leading causes of death and illness in developed countries. ADRs show differential features depending upon genotype, age, sex, race, pathology, drug category, route of administration, and drug–drug interactions. Pharmacogenomics (PGx) provides the physician effective clues for optimizing drug efficacy and safety in major problems of health such as cardiovascular disease and associated disorders, cancer and brain disorders. Important aspects to be considered are also the impact of immunopharmacogenomics in cutaneous ADRs as well as the influence of genomic factors associated with COVID-19 and vaccination strategies. Major limitations for the routine use of PGx procedures for ADRs prevention are the lack of education and training in physicians and pharmacists, poor characterization of drug-related PGx, unspecific biomarkers of drug efficacy and toxicity, cost-effectiveness, administrative problems in health organizations, and insufficient regulation for the generalized use of PGx in the clinical setting. The implementation of PGx requires: (i) education of physicians and all other parties involved in the use and benefits of PGx; (ii) prospective studies to demonstrate the benefits of PGx genotyping; (iii) standardization of PGx procedures and development of clinical guidelines; (iv) NGS and microarrays to cover genes with high PGx potential; and (v) new regulations for PGx-related drug development and PGx drug labelling.

Association between ABCB1 polymorphisms and response to antiepileptic drugs among Jordanian epileptic patients

BACKGROUND

Genetic polymorphisms of drug efflux transporters as ATP-binding cassette subfamily B, member 1 (ABCB1) have been suggested to modulate antiepileptic drugs (AEDs) response. We aimed to explore the association of ABCB1 polymorphisms and AEDs resistance among epileptic patients.

METHODS

A total of 86 Jordanian epileptic patients treated with AEDs was included in the study. DNA was extracted from blood samples and genotyping and haplotypes analyses were conducted for Nine single nucleotide polymorphisms (SNPs) on the ABCB1 gene.

RESULTS

Data revealed that none of the examined SNPs were associated with resistance to AEDs neither on the level of alleles nor genotypes. However, strong association was found between rs2235048 (OR = 10.6; 95%CI = [1.89-59.8], p= 0.01), rs1045642 (OR = 14; 95%CI = [1.3-156.7], p= 0.02), rs2032582 (OR = 9.1; 95%CI = [1.4-57.3], p= 0.04) and rs1128503 (OR = 18.7; 95%CI = [1.6-222.9], p= 0.02), ABCB1 polymorphisms and resistance to AEDs among females but not males. Haplotype analysis revealed statistically significant associations. The strongest significant associations were for haplotypes containing 2677G_1236 T in two-SNPshaplotypes (OR = 4.2; 95%CI = [1.2-14.9], p = 0.024); three-SNPs-haplotypes (OR = 4.2; 95% CI = [1.2-14.9], p = 0.02); four-SNPs-haplotypes (OR = 4.1; 95%CI = [1.2-14.3], p = 0.026).

CONCLUSION

Data suggests that there is a gender dependent association between ABCB1 genetic polymorphisms and response to AEDs. Additionally, ABCB1 haplotypes influence the response to AEDs. Further investigation is needed to confirm the results of this study.

Meta-analysis of probability estimates of worldwide variation of CYP2D6 and CYP2C19

Extensive migration has led to the necessity of knowledge regarding the treatment of migrants with different ethnical backgrounds. This is especially relevant for pharmacological treatment, because of the significant variation between migrant groups in their capacity to metabolize drugs. For psychiatric medications, CYP2D6 and CYP2C19 enzymes are clinically relevant. The aim of this meta-analysis was to analyze studies reporting clinically useful information regarding CYP2D6 and CYP2C19 genotype frequencies, across populations and ethnic groups worldwide. To that end, we conducted a comprehensive meta-analysis using Embase, PubMed, Web of Science, and PsycINFO (>336,000 subjects, 318 reports). A non-normal metabolizer (non-NM) probability estimate was introduced as the equivalent of the sum-prevalence of predicted poor, intermediate, and ultrarapid metabolizer CYP2D6 and CYP2C19 phenotypes. The probability of having a CYP2D6 non-NM predicted phenotype was highest in Algeria (61%) and lowest in Gambia (2.7%) while the probability for CYP2C19 was highest in India (80%) and lowest in countries in the Americas, particularly Mexico (32%). The mean total probability estimates of having a non-NM predicted phenotype worldwide were 36.4% and 61.9% for CYP2D6 and CYP2C19, respectively. We provide detailed tables and world maps summarizing clinically relevant data regarding the prevalence of CYP2D6 and CYP2C19 predicted phenotypes and demonstrating large inter-ethnic differences. Based on the documented probability estimates, pre-emptive pharmacogenetic testing is encouraged for every patient who will undergo therapy with a drug(s) that is metabolized by CYP2D6 and/or CYP2C19 pathways and should be considered in case of treatment resistance or serious side effects.

Pharmacogenetics of tamoxifen therapy in Asian populations: from genetic polymorphism to clinical outcomes

BACKGROUND

Compared with western countries, Asian breast cancer patients have unique pathological and biological characteristics. Most of them are premenopausal women with HR positive. Tamoxifen as the first-line drug for premenopausal women with HR+ is involved in multiple enzymes and transporters during metabolizing and transporting process. Variants that cause decreased or inactive gene products leading to abnormal responses in tamoxifen therapy have well been studied in western countries, whereas such information is much less reported in Asian populations.

OBJECTIVE

In order to elucidate the relationship between genetic variants and tamoxifen-induced individual drug reactions in different Asian populations and further identify genotypes/phenotypes with potential therapeutic significance.

METHODS

We reviewed the frequencies of genetic variants in major enzymes and transporter genes involved in the metabolism and transport of tamoxifen across Asian populations as well as significant correlations between genotypes/metabolic phenotypes and metabolites concentrations or BC clinical outcomes.

RESULTS

Significant inter-ethnic differences in allele frequencies was found among Asian populations, such as CYP2D6*4, *10, *41, CYP2C9*2, ABCB1 C3435T and SLCO1B1*5, and CYP2D6*10/*10 is the most common genotype correlated with adverse clinical outcomes. Moreover, we summarized the barriers and controversies of implementing pharmacogenetics in tamoxifen therapy and concluded that more population-specific pharmacogenetic studies are needed in the future.

CONCLUSION

This review revealed more systematic pharmacogenomics of genes involved in the metabolism and transport besides CYP2D6, are required to optimize the genotyping strategies and guide the personalized tamoxifen therapy in Asian populations.

CYP2C19 Allele Frequencies in Over 2.2 Million Direct-to-Consumer Genetics Research Participants and the Potential Implication for Prescriptions in a Large Health System

Understanding the prevalence of clinically relevant pharmacogenetic variants using large unselected populations is critical for gauging the potential clinical impact of widespread preemptive pharmacogenetic testing. To this end, we assessed the frequencies and ethnic distribution of the three most common CYP2C19 alleles (*2, *3, and *17) in 2.29 million direct-to-consumer genetics research participants (23andMe, Sunnyvale, CA). The overall frequencies of *2, *3, and *17 were 15.2%, 0.3%, and 20.4%, respectively, but varied by ethnicity. The most common variant diplotypes were *1/*17 at 26% and *1/*2 at 19.4%. The less common *2/*17, *17/*17, and *2/*2 genotypes occurred at 6.0%, 4.4%, and 2.5%, respectively. Overall, 58.3% of participants had at least one increased-function or no-function CYP2C19 allele. To better understand how this high frequency might impact a real patient population, we examined the prescription rates (Rx) of high-pharmacogenetic-risk medications metabolized by CYP2C19 using the University of California at San Francisco (UCSF) health system's anonymized database of over 1.25 million patients. Between 2012 and 2019, a total of 151,068 UCSF patients (15.8%) representing 5 self-reported ethnicities were prescribed one or more high-pharmacogenetic-risk CYP2C19 medications: proton pump inhibitors (145,243 Rx), three selective serotonin reuptake inhibitor antidepressants (54,463 Rx), clopidogrel (14,376 Rx), and voriconazole (2,303 Rx).

Influence of Genetic Admixture Components on CYP3A5*3 Allele-Associated Hypertension in Amerindian Populations From Northwest Mexico

CYP3A5 metabolizes endogenous substrates and ~30% of prescription drugs. The CYP3A5 gene contains an active CYP3A5*1 allele, and a non-functional version, the CYP3A5*3 (rs776746), with consequences for drug therapeutic responses and side effects. Both CYP3A5*1 and *3 have been associated with hypertension. The frequency of CYP3A5*3 varies between populations of different ancestries, with Europeans having the highest allele frequency (> 90%). Given the importance of CYP3A5*3 in drug response and hypertension development, the aim of the present study was to evaluate the frequency of this polymorphism and its association with hypertension in vulnerable indigenous populations in Mexico. A total of 372 subjects were recruited from eight ethnic groups in Northwest Mexico. Systolic (SBP), diastolic (DBP), and median (MBP) blood pressures as well as body mass index (BMI) were measured. Ancestry was evaluated through STR analysis, and the CYP3A5*1/*3 polymorphisms were identified using real-time PCR with TaqMan® probes. Higher frequencies of CYP3A5*1 and *3 were observed in groups with higher (>90%) and lower (<90%) Amerindian ancestry, respectively. The CYP3A5*3/*3 genotype was more frequent in indigenous women with higher SBP and DBP values. On the other hand, the *1 allele showed a protective effect against both high SBP (OR, 0.38; 95% CI, 0.17-0.83, p = 0.001) and DBP (OR 0.38, 95% CI 0.18-0.81, p = 0.007) in women. This association remained significant after adjusting for BMI and age for diastolic (OR, 0.38; 95% CI, 0.17-0.84, p = 0.011) and systolic BP (OR, 0.33; 95% CI, 0.15-0.76, p = 0.005) BP levels in women. Thus, the frequency of CYP3A5*3 varies between groups and seems to depend on ancestry, and CYP3A5*1 decreases the risk of hypertension in Mexican indigenous women. This population analysis of CYP3A5*1/*3 has profound implications not only for the susceptibility to diseases, such as hypertension, but also for safer drug administration regimens, assuring better therapeutic responses and fewer side effects.

The effect of genetic and nongenetic factors on warfarin dose variability in Qatari population

The objective of this study is to estimate the prevalence of VKORC1, CYP2C9, and CYP4F2 genetic variants and their contribution to warfarin dose variability in Qataris. One hundred and fifty warfarin-treated Qatari patients on a stable dose and with a therapeutic INR for at least three consecutive clinic visits were recruited. Saliva samples were collected using Oragene DNA self-collection kit, followed by DNA purification and genotyping via TaqMan Real-Time-PCR assay. The population was stratified into derivation and validation cohorts for the dosing model. The minor allele frequency (MAF) of VKORC1 (-1639G>A) was A (0.47), while the MAF's for the CYP2C9*2 and *3 and CYP4F2*3 were T (0.12), C (0.04) and T (0.43), respectively. Carriers of at least one CYP2C9 decreased function allele (*2 or *3) required lower median (IQR) warfarin doses compared to noncarriers [24.5 (14.5) mg/week vs. 35 (21) mg/week, p < 0.001]. Similarly, carriers of each additional copy of (A) variant in VKORC1 (-1639G>A) led to reduction in warfarin dose requirement compared to noncarriers [21(7.5) vs. 31.5(18.7) vs. 43.7(15), p < 0.0001]. CYP4F2*3 polymorphism on the other hand was not associated with warfarin dose. Multivariate analysis on the derivation cohort (n = 104) showed that a dosing model consisting of hypertension (HTN), heart failure (HF), VKORC1 (-1639G>A), CYP2C9*2 & *3, and smoking could explain 39.2% of warfarin dose variability in Qataris (P < 0.001). In the validation cohort (n = 45), correlation between predicted and actual warfarin doses was moderate (Spearman's rho correlation coefficient = 0.711, p < 0.001). This study concluded that VKORC1 (-1639G>A), CYP2C9*2 & *3 are the most significant predictors of warfarin dose along with HTN, HF and smoking.

Effects of CYP2C9 and VKORC1 polymorphisms on warfarin sensitivity and responsiveness during the stabilization phase of therapy

The main objective of this study is to assess the effects of CYP2C9 and VKORC1 polymorphisms on warfarin sensitivity and responsiveness in a Jordanian population during the stabilization phase of treatment. This study was conducted at the Queen Alia Heart Institute (QAHI) anticoagulation clinic in Amman, Jordan. We assessed three CYP2C9 (rs1799853, rs1057910, rs4086116) and four VKORC1 (rs10871454, rs8050894, rs9934438, rs17708472) polymorphisms in 139 Jordanian cardiovascular patients. Demographic and clinical data were also collected. Of the 139 patients in the cohort, 80% had the VKORC1 polymorphisms rs10871454 and rs9934438, while 22.3% and 24.5% of patients had the rs1799853 and rs1057910 CYP2C9 alleles, respectively. Carriers of the CYP2C9 polymorphisms rs1057910 and rs4086116 had an increased risk of warfarin sensitivity compared to subjects with no or only one polymorphism. Similarly, carriers of all four VKORC1 variants had an increased risk of warfarin sensitivity (over anticoagulation) compared to those with no or only one polymorphism. Patients with a CYP2C9 or VKORC1 polymorphism required significantly lower doses than patients with no polymorphisms. The presence of any of CYP2C9 or VKORC1 polymorphisms is associated with sensitivity to warfarin during the stabilization period. Being a CYP2C9 or VKORC1 polymorphism carrier is associated with a variation in doses required to achieve the therapeutic INR compared to non-carrier patients.

Donor Genotype and Intragraft Expression of CYP3A5 Reflect the Response to Steroid Treatment During Acute Renal Allograft Rejection

BACKGROUND

Glucocorticoid (GC)-refractory acute rejection (AR) is a risk factor for inferior renal allograft outcome. We investigated genetic predisposition to the response to steroid treatment of acute allograft rejection.

METHODS

Single nucleotide polymorphisms of genes involved in GC signaling (GR, GLCCI1) and drug metabolism and transport (CYP3A5, ABCB1, and PXR) were analyzed in kidney transplant recipients (1995-2005, Leiden cohort, n = 153) treated with methylprednisolone. Significant associations were verified in a second cohort (Berlin cohort, n = 66).

RESULTS

Patients who received a CYP3A5*1 allele expressing allograft had a lower risk of resistance to methylprednisolone during AR (odds ratio, 0.29; 95% confidence interval, 0.11-0.79; P = 0.016 in combined cohorts analysis). No differences were observed for GC signaling or other drug metabolism/transport-related genes. Both before transplantation (n = 69) and at time of AR (n = 88), tissue CYP3A5 mRNA expression was significantly higher in CYP3A5*1 allele expressing donor kidneys than in CYP3A5*3/*3 allografts (P < 0.00001). Moreover, steroid-responsive patients (n = 64) expressed significantly higher intragraft CYP3A5 mRNA levels compared to steroid-refractory patients (n = 42) in AR (P = 0.006).

CONCLUSIONS

CYP3A5 protein expression was detected in tubular epithelial cells and inflammatory cells within the grafts. Our findings show that steroid resistance during AR is associated with donor genotype and intragraft expression levels of CYP3A5.

Impact of Genetic Polymorphisms on Phenytoin Pharmacokinetics and Clinical Outcomes in the Middle East and North Africa Region

BACKGROUND

Genetic polymorphisms are known to influence outcomes with phenytoin yet effects in the Middle East and North Africa region are poorly understood.

OBJECTIVES

The objective of this systematic review was to evaluate the impact of genetic polymorphisms on phenytoin pharmacokinetics and clinical outcomes in populations originating from the Middle East and North Africa region, and to characterize genotypic and allelic frequencies within the region for genetic polymorphisms assessed.

METHODS

MEDLINE (1946-3 May, 2017), EMBASE (1974-3 May, 2017), Pharmacogenomics Knowledge Base, and Public Health Genomics Knowledge Base online databases were searched. Studies were included if genotyping and analyses of phenytoin pharmacokinetics were performed in patients of the Middle East and North Africa region. Study quality was assessed using a National Institutes of Health assessment tool. A secondary search identified studies reporting genotypic and allelic frequencies of assessed genetic polymorphisms within the Middle East and North Africa region.

RESULTS

Five studies met the inclusion criteria. CYP2C9, CYP2C19, and multidrug resistance protein 1 C3435T variants were evaluated. While CYP2C9*2 and *3 variants significantly reduced phenytoin metabolism, the impacts of CYP2C19*2 and *3 variants were unclear. The multidrug resistance protein 1 CC genotype was associated with drug-resistant epilepsy, but reported impacts on phenytoin pharmacokinetics were conflicting. Appreciable variability in minor allele frequencies existed both between and within countries of the Middle East and North Africa region.

CONCLUSIONS

CYP2C9 decrease-of-function alleles altered phenytoin pharmacokinetics in patients originating from the Middle East and North Africa region. The impacts of CYP2C19 and multidrug resistance protein 1 C3435T variants on phenytoin pharmacokinetic and clinical outcomes are unclear and require further investigation. Future research should focus on the clinical outcomes associated with phenytoin therapy. PROSPERO 2017: CRD42017057850.

Effects of Lemon and Seville Orange Juices on the Pharmacokinetic Properties of Sildenafil in Healthy Subjects

PURPOSE

Several severe drug interactions have been reported when sildenafil, a potent drug for the treatment of erectile dysfunction, is co-administered with drugs or herbal remedies that inhibit cytochrome P450 (CYP) 3A4. This study evaluates the effects of two citrus fruit juices, lemon and Seville orange, on the pharmacokinetics of sildenafil in male healthy subjects following a single oral dose.

METHODS

We conducted an open-label, three-way crossover study in nine healthy male volunteers. Participants received a single oral dose of sildenafil (50 mg) after pretreatment with 250 mL of either water (control), undiluted lemon juice, or Seville orange juice for 3 consecutive days. All subjects were monitored for adverse effects during the study period. Plasma samples were collected for 12 h after dosing and analyzed for sildenafil concentration.

RESULTS

Compared with pretreatment with water, Seville orange juice significantly increased the area under the plasma concentration-time curve from time zero to infinity and the peak plasma concentration of sildenafil by 44 % (90 % confidence interval [CI] 30-60) and 18 % (90 % CI 108-129), respectively, without affecting the time to reach peak plasma concentration. Additionally, Seville orange juice significantly reduced the apparent oral clearance of sildenafil by 30 % (90 % CI 63-75) without affecting its elimination half-life. In contrast, lemon juice did not cause any significant alterations in the pharmacokinetics of sildenafil. There was no significant treatment-related adverse effects reported during the study.

CONCLUSIONS

Although it is considered as a moderate CYP3A4 inhibitor, Seville orange only caused a mild increase in exposure to sildenafil after a single oral dose, without manifestation of any adverse effects. The enhanced bioavailability of sildenafil by Seville orange may be attributed to inhibition of its intestinal first-pass effect (CYP3A4 and or p-glycoprotein). Lemon juice, in contrast, had no effects on the pharmacokinetics of sildenafil.

Genetic polymorphisms study of pharmacogenomic VIP variants in Han ethnic of China's Shaanxi province

BACKGROUND

Multiple factors include genetic and non-genetic interactions induce to different drug response among different individuals. Lots of researches proved that different frequencies of genetic variants exists different ethnic groups. The aim of this study was to screen Han volunteers in Shaanxi for VIP gene polymorphisms.

MATERIALS AND METHODS

We genotyped 80 Very Important Pharmacogenes (VIP) (selected from the PharmGKB database) in 192 unrelated, healthy Han ethnic adults from Shaanxi, the northwest of China, and then analyzed genotyping data wtih Structure and F-statistics (Fst) analysis.

RESULTS

We compared our data with 15 other populations (Deng, Kyrgyz, Tajik, Uygur and 11 HapMap populations), and found the frequency distribution of Han population in Shaanxi is most similar with CHB. Also, Structure and Fst showed that Shaanxi Han has a closest genetic background with CHB.

CONCLUSIONS

Our study have supplemented the Han Chinese data related to pharmacogenomics and illustrated differences in genotypic frequencies of selected VIP variants' among the Han population and 15 other populations.

Gene polymorphism of CYP2C19*2, *3 and CYP3A4*1B and early stent thrombosis: case reports and literature review

We present two clinical cases of acute and subacute coronary artery stent thrombosis in patients treated at the Department of Interventional Cardiology in Aktobe, Kazakhstan. Our results draw attention to the impact of CYP3A4*1B on the clinical effect of clopidogrel during dual antiplatelet therapy after PCI. The genotyping performed at the Laboratory of Molecular Cardiology of Institute of Cardiology of Lithuanian University of Health Sciences in Lithuania revealed that both patients were homozygous carriers of CYP3A4*1B*1B. They also were carriers of CYP2C19 loss-of-function *2 or *3 alleles (*1*2 and *1*3, respectively).

Interethnic variation of CYP2C19 alleles, 'predicted' phenotypes and 'measured' metabolic phenotypes across world populations

The present study evaluates the worldwide frequency distribution of CYP2C19 alleles and CYP2C19 metabolic phenotypes ('predicted' from genotypes and 'measured' with a probe drug) among healthy volunteers from different ethnic groups and geographic regions, as well as the relationship between the 'predicted' and 'measured' CYP2C19 metabolic phenotypes. A total of 52 181 healthy volunteers were studied within 138 selected original research papers. CYP2C19*17 was 42- and 24-fold more frequent in Mediterranean-South Europeans and Middle Easterns than in East Asians (P<0.001, in both cases). Contrarily, CYP2C19*2 and CYP2C19*3 alleles were more frequent in East Asians (30.26% and 6.89%, respectively), and even a twofold higher frequency of these alleles was found in Native populations from Oceania (61.30% and 14.42%, respectively; P<0.001, in all cases), which may be a consequence of genetic drift process in the Pacific Islands. Regarding CYP2C19 metabolic phenotype, poor metabolizers (PMs) were more frequent among Asians than in Europeans, contrarily to the phenomenon reported for CYP2D6. A correlation has been found between the frequencies of CYP2C19 poor metabolism 'predicted' from CYP2C19 genotypes (gPMs) and the poor metabolic phenotype 'measured' with a probe drug (mPMs) when subjects are either classified by ethnicity (r=0.94, P<0.001) or geographic region (r=0.99, P=0.002). Nevertheless, further research is needed in African and Asian populations, which are under-represented, and additional CYP2C19 variants and the 'measured' phenotype should be studied.

Gene-environment interactions in esophageal cancer

Esophageal cancer (EC) is one of the most common malignancies in low- and medium-income countries and represents a disease of public health importance because of its poor prognosis and high mortality rate in these regions. The striking variation in the prevalence of EC among different ethnic groups suggests a significant contribution of population-specific environmental and dietary factors to susceptibility to the disease. Although individuals within a demarcated geographical area are exposed to the same environment and share similar dietary habits, not all of them will develop the disease; thus genetic susceptibility to environmental risk factors may play a key role in the development of EC. A wide range of xenobiotic-metabolizing enzymes are responsible for the metabolism of carcinogens introduced via the diet or inhaled from the environment. Such dietary or environmental carcinogens can bind to DNA, resulting in mutations that may lead to carcinogenesis. Genes involved in the biosynthesis of these enzymes are all subject to genetic polymorphisms that can lead to altered expression or activity of the encoded proteins. Genetic polymorphisms may, therefore, act as molecular biomarkers that can provide important predictive information about carcinogenesis. The aim of this review is to discuss our current knowledge on the genetic risk factors associated with the development of EC in different populations; it addresses mainly the topics of genetic polymorphisms, gene-environment interactions, and carcinogenesis. We have reviewed the published data on genetic polymorphisms of enzymes involved in the metabolism of xenobiotics and discuss some of the potential gene-environment interactions underlying esophageal carcinogenesis. The main enzymes discussed in this review are the glutathione S-transferases (GSTs), N-acetyltransferases (NATs), cytochrome P450s (CYPs), sulfotransferases (SULTs), UDP-glucuronosyltransferases (UGTs), and epoxide hydrolases (EHs), all of which have key roles in the detoxification of environmental and dietary carcinogens. Finally, we discuss recent advances in the study of genetic polymorphisms associated with EC risk, specifically with regard to genome-wide association studies, and examine possible challenges of case-control studies that need to be addressed to better understand the interaction between genetic and environmental factors in esophageal carcinogenesis.

Comparative study of polymorphism frequencies of the CYP2D6, CYP3A5, CYP2C8 and IL-10 genes in Mexican and Spanish women with breast cancer

AIM

Pharmacogenetic studies in breast cancer (BC) may predict the efficacy of tamoxifen and the toxicity of paclitaxel and capecitabine. We determined the frequency of polymorphisms in the CYP2D6 gene associated with activation of tamoxifen, and those of the genes CYP2C8, CYP3A5 and DPYD associated with toxicity of paclitaxel and capecitabine. We also included a IL-10 gene polymorphism associated with advanced tumor stage at diagnosis.

PATIENTS & METHODS

Genomic DNAs from 241 BC patients from northeast Mexico were genotyped using DNA microarray technology.

RESULTS

For tamoxifen processing, CYP2D6 genotyping predicted that 90.8% of patients were normal metabolizers, 4.2% ultrarapid, 2.1% intermediate and 2.9% poor metabolizers. For paclitaxel and the CYP2C8 gene, 75.3% were normal, 23.4% intermediate and 1.3% poor metabolizers. Regarding the DPYD gene, only one patient was a poor metabolizer. For the IL-10 gene, 47.1% were poor metabolizers.

CONCLUSION

These results contribute valuable information towards personalizing BC chemotherapy in Mexican women.

ABCB1 C3435T and CYP2C19*2 polymorphisms in a Palestinian and Turkish population: A pharmacogenetic perspective to clopidogrel

Clopidogrel is an antiplatelet drug used to prevent recurrent ischemic events after acute coronary syndrome and/or coronary stent implantation. Single nucleotide polymorphisms (SNPs) such as CYP2C19*2 and ABCB1 C3435T have been found to play a role in different individual responses to clopidogrel. Since the prevalence of these SNPs is generally known to differ from one population to another, the aim of this study was to examine their prevalence in both a Palestinian and Turkish population. One hundred unrelated Palestinian subjects and 100 unrelated Turkish subjects were analyzed for CYP2C19*2 and ABCB1 C3435T polymorphisms by the amplification refractory mutation system (ARMS). Results showed an ABCB1 3435 T allele frequency of 0.46 (95% CI 0.391 to 0.529) in the Palestinian sample and 0.535 (95% CI 0.4664 to 0.6036) in the Turkish sample. CYP2C19*2 allele frequency was 0.095 (95% CI 0.0558 to 0.134) in the Palestinian sample and 0.135 (95% CI 0.088 to 0.182) in the Turkish sample. Our results provide information about the prevalence of the polymorphisms related to clopidogrel response in both the Palestinian and Turkish populations, in order to improve the safety and efficacy of clopidogrel through use of genetically guided, individualized treatment. The prevalence of these clinically significant alleles shed light on the importance of testing them before prescribing clopidogrel.

Relationships between CYP1A1 genetic polymorphisms and bladder cancer risk: a meta-analysis

This meta-analysis aims at evaluating the relationships between CYP1A1 genetic polymorphisms and bladder cancer risk. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched from inception through November 1st, 2013 without language restrictions. Meta-analysis was conducted with the use of the STATA 12.0 software. The relationships were evaluated by calculating the pooled odds ratios (ORs) and their 95% confidence intervals (CIs). Eight case-control studies with a total of 2120 bladder cancer patients and 2061 healthy subjects met the inclusion criteria. Ten common polymorphisms in the CYP1A1 gene were assessed. The results of our meta-analysis suggested that CYP1A1 genetic polymorphisms might be strongly correlated with an increased risk of bladder cancer (allele model: OR=1.23, 95%CI=1.08-1.39, p=0.001; dominant model: OR=1.25, 95%CI=1.07-1.46, p=0.005; respectively), especially for 11599G>C, 2455A>G, 3810T>C, and 113T>C polymorphisms. A subgroup analysis was done to investigate the effect of ethnicity on an individual's risk of bladder cancer. Our results revealed positive significant correlations between CYP1A1 genetic polymorphisms and an increased risk of bladder cancer among Asians (allele model: OR=1.33, 95%CI=1.08-1.65, p=0.009; dominant model: OR=1.37, 95%CI=1.02-1.85, p=0.034; respectively), but not among Caucasians (all p<0.05). Our findings provide convincing evidence that CYP1A1 genetic polymorphisms may contribute to susceptibility to bladder cancer, especially for 11599G>C, 2455A>G, 3810T>C, and 113T>C polymorphisms among Asians.

Genotyping of CYP2C9 and VKORC1 in the Arabic population of Al-Ahsa, Saudi Arabia

Polymorphisms in the genes encoding CYP2C9 enzyme and VKORC1 reductase significantly influence the dose variability of coumarinic oral anticoagulants (COAs). Substantial inter- and intraethnic variability exists in the frequencies of CYP2C9*2 and *3 and VKORC1 -1639A alleles. However, the prevalence of CYP2C9 and VKORC1 genetic variants is less characterized in Arab populations. A total of 131 healthy adult subjects from the Al-Ahsa region of Saudi Arabia were genotyped for the CYP2C9 *2 and *3 and VKORC1 -1639G>A polymorphisms by PCR-RFLP method. The frequencies of the CYP2C9 *2 and *3 and VKORC1 -1639A alleles were 13.3%, 2.3%, and 42.4%, respectively, with no subjects carrying 2 defective alleles. The frequencies of the CYP2C9 *3 and VKORC1 -1639A alleles were significantly lower than those reported in different Arabian populations. None of the subjects with the VKORC1 -1639AA genotype were carriers of CYP2C9 *1/*3 genotypes that lead to sensitivity to COAs therapy. The low frequency of the CYP2C9 *3 allele combined with the absence of subjects carrying 2 defective CYP2C9 alleles suggests that, in this specific population, pharmacogenetic COAs dosing may mostly rely upon VKORC1 genotyping.