Cytochrome P450 2C19 Gene Polymorphism Research Articles

Effect of cytochrome P450 2C19 (CYP2C19) gene polymorphism and clopidogrel reactivity on long term prognosis of patients with coronary heart disease after PCI.

To investigate the impact of CYP2C19 gene polymorphism on clopidogrel reactivity and its association with long-term clinical outcome in patients with coronary heart disease (CHD) undergoing percutaneous coronary intervention (PCI). In total, 675 patients were enrolled. Based on the platelet inhibition rate, patients were categorized into two groups: clopidogrel low responsiveness (CLR) and normal clopidogrel responsiveness (NCR). The CLR group was divided into ticagrelor and clopidogrel group based on the antiplatelet drugs used in the follow-up treatment. Patients were classified into three groups (normal metabolizer, intermediate metabolizer, and poor metabolizer) based on the CYP2C19 genotype. We aimed to evaluate the impact of CYP2C19 gene polymorphism on clopidogrel reactivity. The cumulative rates of 12-month all-cause deaths, major adverse cardiovascular events (MACCEs), and bleeding events were calculated. CLR was observed in 44.4% of the overall population. Significant differences were observed in the platelet inhibition rate of clopidogrel among the three metabolic genotypes (P < 0.05). At the 12-month follow-up, 13 patients (1.9%) died and 96 patients (14.2%) experienced MACCEs. Patients with CLR (9.6% vs. 11.7% vs. 22.1%, P < 0.05) or poor metabolizer (10.7% vs. 16.4% vs. 22.6%, P = 0.026) experienced a higher rate of MACCEs. A MACCEs risk score between zero and two was calculated. The highest incidence of MACCEs significantly increased with the 2-positive results, and the area under the curve (AUC) was 0.712 (95% CI: 0.650-0.774, P < 0.05). There was no significant difference between the group with a score of one and the occurrence of MACCEs (P > 0.05). Low response to clopidogrel in CHD patients is correlated with CYP2C19 gene polymorphism. CYP2C19 genotyping combined with platelet reactivity is an independent predictor of 12-months MACCEs in patients with clopidogrel treatment after PCI, which is better than either test alone.

The Association between CYP2C19 Genetic Polymorphism and Prognosis in Patients Receiving Endovascular Therapy.

Potentially substantial impacts on the prognosis have been observed in individuals undergoing endovascular treatment due to cytochrome P450 2c19 (CYP2C19) polymorphism. In an attempt to improve prognosis and lower the recurrence rate, this study investigated the CYP2C19 polymorphism in acute ischemic stroke patients. A retrospective analysis was performed on 292 patients with cerebral infarction who had acute endovascular recanalization at the Department of Neurology of Chongqing Hospital of Traditional Chinese Medicine between May 2017 and 2019. The patients were categorized into rapid-, medium-, and slow-metabolism groups based on CYP2C19 gene polymorphism, and their prognosis was monitored. In addition, the prognosis of 188 patients selectively receiving carotid artery stenting at a selected time was also observed. Among the 292 cerebral infarction cases receiving acute endovascular recanalization, the patients in the CYP2C19 rapid-metabolism group regularly took clopidogrel and aspirin combined with antiplatelet therapy and suffered from reoccurrence of apoplexy and cerebral hemorrhage; the 90-day good prognosis had a statistical difference (P < 0.05, prognostic assessment includes hospitalization and 6 months after discharge) and the other adverse events had no statistical difference (including mortality). The 188 patients selectively receiving carotid artery stenting had a recurrence of apoplexy, cerebral hemorrhage, and restenosis rate with a statistical difference (P < 0.05), and the other adverse events had no statistical difference. In conclusion, the findings of the current study indicate that irrespective of whether patients are undergoing selective carotid artery stenting or acute endovascular recanalization, those with rapid CYP2C19 metabolism have a significantly lower likelihood of experiencing adverse prognostic events compared to those with intermediate and slow metabolism. Furthermore, this group also has a more favorable prognosis than the other two groups.

Differences in the Proportion of CYP2C19 Loss-of-Function Between Cerebral Infarction and Coronary Artery Disease Patients.

Cytochrome P450 2C19 (CYP2C19) genotypes and metabolic phenotypes (extensive metabolizer (EM), intermediate metabolizer (IM), and poor metabolizer (PM)) are related to the metabolism of therapeutic drugs for cardiovascular and cerebrovascular diseases. This study aimed to investigate the differences of CYP2C19 gene polymorphism distribution between coronary artery disease (CAD) patients and cerebral infarction (CI) patients. We identified 413 CI patients, 509 CAD patients, and 241 CI+CAD patients from 2016 to 2020 and studied genotypes of CYP2C19 rs4986893 (636G>A) and rs4244285 (681G>A) polymorphisms using PCR-gene chip detection method. Differences in CYP2C19 genotypes and metabolic phenotypes between the groups were compared. To analyze the efficacy of CYP2C19 metabolic phenotypes in discriminating between cerebral infarction and coronary artery disease, multiple logistic regression analysis was conducted after adjusting for gender, age, smoking history, drinking history, hypertension, and diabetes. There were significant differences in the distribution of CYP2C19 genotypes and metabolic phenotypes between CI and CAD patients. The results of multivariate logistic regression (adjusted for sex, age, smoking, drinking, hypertension, and diabetes) indicated that CYP2C19 IM phenotype (IM vs EM: OR 1.443, 95% CI: 1.086-1.918, P=0.011) and CYP2C19 IM+PM phenotype (IM or PM vs EM: OR 1.440, 95% CI: 1.100-1.885, P=0.008) may be indicators of CI from CAD. CYP2C19 EM metabolic phenotype was dominant in CAD patients, and CYP2C19 IM metabolic phenotype was dominant in CI patients. After adjusting for other confounding factors, patients with the CYP2C19 IM metabolic phenotype were more likely to develop CI than CAD.

The relationship between genetic polymorphism of CYP2C19 and the efficacy of Helicobacter pylori eradication therapy in children

Objective: To investigate the relationship between genetic polymorphisms of cytochrome P450 2C19 (CYP2C19) and the efficacy of Helicobacter pylori (Hp) eradication therapy in children. Methods: The retrospective cohort study was conducted on 125 children with gastroscopy and positive rapid urease test (RUT) from September 2016 to December 2018 who presented to the Children's Hospital of Zhejiang University School of Medicine due to gastrointestinal symptoms including nausea, vomiting, abdominal pain, bloating, acid reflux, heartburn, chest pain, vomiting blood and melena. Hp culture and drug susceptibility test were carried out with gastric antrum mucosa before treatment. All the patients completed 2 weeks of standardized Hp eradication therapy and had 13C urea breath test 1 month after that, which was used to evaluate the curative effect. The DNA of gastric mucosa after RUT was analyzed and CYP2C19 gene polymorphism was detected. Children were grouped according to metabolic type. Combined with the results of Hp culture and drug susceptibility, the relationship between CYP2C19 gene polymorphism and the efficacy of Hp eradicative treatment was analyzed in children. Chi square test was used for row and column variables, and Fisher exact test was used for comparison between groups. Results: One hundred and twenty five children were enrolled in the study, of whom 76 were males and 49 females. The genetic polymorphism of CYP2C19 in these children found poor metabolizer (PM) of 30.4% (38/125), intermediate metabolizer (IM) of 20.8% (26/125), normal metabolizer (NM) of 47.2% (59/125), rapid metabolizer (RM) of 1.6% (2/125), and ultrarapid metabolizer (UM) of 0. There were statistically significant in positive rate of Hp culture among these groups (χ2=124.00, P<0.001). In addition, the successful rates of Hp eradication in PM, IM, NM and RM genotypes were 84.2% (32/38), 53.8% (14/26), 67.8% (40/59), and 0, respectively, with significant differences (χ2=11.35, P=0.010); those in IM genotype was significantly lower than that in PM genotype (P=0.011). With the same standard triple Hp eradicative regimen, the successful rate of Hp eradication for IM type was 8/19, which was lower than that of PM (80.0%, 24/30) and NM type (77.3%, 34/44) (P=0.007 and 0.007, respectively). There was a significant difference in the efficacy of Hp eradication treatment among different genotypes (χ2=9.72, P=0.008). According to the clarithromycin susceptibility result, the successful rate of Hp eradication treatment for IM genotype was 4/15 in the sensitive group and 4/4 in the drug-resistant group (χ2=6.97, P=0.018). Conclusions: The genetic polymorphism of CYP2C19 in children is closely related to the efficacy of Hp eradication treatment. PM has a higher successful rate of eradication treatment than the other genotypes.

Analysis of CYP2C19 gene polymorphism and influencing factors of pharmacological response of clopidogrel in patients with cerebral infarction in Zhejiang, China.

Certain genetic and non-genetic factors may cause damaged platelet inhibition by clopidogrel. We aimed to determine the effect of cytochrome P4502C19 (CYP2C19) polymorphism, along with other clinical factors, on the platelet response to clopidogrel in patients with acute ischemic stroke (AIS). A total of 214 patients with AIS receiving clopidogrel at a maintenance dose of 75 mg daily admitted to the Ningbo First Hospital between 1 January 2020, and 31 December 2021, were enrolled. Platelet aggregation analysis was performed to determine clopidogrel resistance. Quantitative real-time polymerase chain reaction (QRT-PCR) was used to determine CYP2C19 genotype. Other laboratory data on complete blood count and biochemical parameters were taken from patient medical files. Among the 214 AIS patients treated with clopidogrel in the Ningbo population, the incidence of clopidogrel resistance was approximately 43.9%, and the distribution of CYP2C19 genotypes was highest for CYP2C19(*1/*2) (43.0%), followed by CYP2C19 (*1/*1) (38.8%). The distribution of alleles *1, *2, *3, and *17 was 62.1, 32.5, 4.9, and 0.5%, respectively. A chi-squared test showed that the gene frequencies of alleles *2 and *3 were significantly higher in the clopidogrel-resistant group than in the clopidogrel-sensitive group (p < 0.001), and a Mann-Whitney U-test showed that high HCY levels were significantly correlated with clopidogrel resistance (p < 0.001). Multi-factor logistic regression analysis demonstrated that mutant heterozygous genotype [OR 2.893; 95% confidence interval (CI) 1.456-5.748; p = 0.002], mutant homozygous genotype (OR 4.741; 95% CI 1.828-12.298; p = 0.001), and high HCY levels (OR 1.209; 95% CI 1.072-1.362; p = 0.002) were significantly associated with clopidogrel resistance. According to our results, carrying the CYP2C19*2/*3 allele and high HCY levels are independent risk factors for clopidogrel resistance after clopidogrel therapy in patients with AIS. These two factors should be considered prior to clopidogrel administration.

Relationship between recurrent ischemic events in cerebrovascular disease and cytochrome P450 2C19 gene polymorphism on the basis of thrombelastography.

Recurrent ischemic events in cerebrovascular disease present a difficult problem in clinical practice. The predictive value of cytochrome P450 2C19 (CYP2C19) gene polymorphism and high platelet reactivity for recurrent ischemic events in cerebrovascular disease is not clear. A total of 295 patients with acute ischemic cerebrovascular disease admitted to the cerebrovascular disease center of Northern Theater General Hospital between January 1, 2020 and February 2, 2021 were enrolled in this study. Thrombelastography (TEG) was used to detect platelet reactivity and CYP2C19 gene polymorphism. Among the 118 noncarriers, 97 had normal platelet reactivity and 21 had high platelet reactivity. Of the 177 carriers, 120 showed normal platelet reactivity and 57 showed high platelet reactivity. The area under the curve (AUC) of CYP2C19 gene polymorphism in predicting recurrent ischemic events was 0.66. The regression coefficients of hypertension, stroke history, carriers, and high platelet reactivity with recurrent ischemic events were 0.341, 0.402, 0.358, and 0.281, respectively, with significant positive correlation (P<0.05). Hypertension, stroke history, carriers, and high platelet reactivity are all independent risk factors for recurrent ischemic events. CYP2C19 gene polymorphism and high platelet reactivity can be used as effective predictors of recurrent ischemic events in clinical cerebrovascular disease.

Cytochrome P450 2C19 gene polymorphisms (CYP2C19*2 and CYP2C19*3) in chronic myeloid leukemia patients: in vitro and in silico studies

Polymorphisms in the CYP2C19 have a huge impact on drug processing, out of which CYP2C19*2 and CYP2C19*3 are the most common variants associated with reduced metabolism of drugs. Mechanism by which two variants contribute in poor metabolization of drugs and cancer is not well understood. Here, we hypothesized that the mutations in CYP2C19 gene might affect the risk of chronic myeloid leukemia patients (CML). Present study has two main objectives: first to investigate the allele frequencies of CYP2C19*2 and CYP2C19*3 associated gene polymorphisms in CML patients and to elucidate the structural stability, conformation and functions of protein encoded by such variants. Genotyping of CYP2C19 was performed in 103 CML patients and 103 matched healthy controls. Heterozygous genotype of CYP2C19*2 was higher in CML patients (13.59%) than the controls (4.85%). Whereas, CYP2C19*3 allele frequency was not observed in cases as well as in controls. Furthermore, molecular dynamics (MD) simulation was applied to monitor the structural and conformational effect of above mutants. MD simulation results demonstrated that these mutants formed unstable proteins with distorted conformations, altered residues network and affected drug binding site which led to malfunction of mutant proteins. Hence, the study provides the role of CYP2C19 gene polymorphisms in susceptibility to CML population and explored the molecular basis of malignancies caused which may aid in the development of precise medicine or adjusting the drug dosages so as to reduce the chemotherapeutic side effects. Communicated by Ramaswamy H. Sarma

Concepts of Prakriti (Human Constitution) and its Association with Hematological Parameters, Body Mass Index (BMI), Blood Groups and Genotypes

Background: Ayurveda is an ancient system of personalized medicine, documented and practiced in India since 1500 B.C. According to this system an individual’s basic constitution to a large extent determines predisposition and prognosis to diseases as well as the therapy and life-style regime. Ayurveda describes seven broad Prakriti (Physical constitution) Prakriti is defined as the sum of physical, physiological, psychological traits of an individual which represents genotypes. Objective: In this article we have attempted to narrate concepts of Prakriti and its relation with hematological parameter, body mass index, blood groups and genotypes. Material and Method: Present article is based on critical review of Ayurvedic textual information, published research works, modern literature and research works conducted at various institutes. The possible correlation has been made between collected information and has been presented in systematic way. Result: In Pitta Prakriti individual’s hematological parameters like Hemoglobin (Hb%), Packed cell volume (PCV), and Red blood corpuscles (RBC) count are significantly on the higher side of normal range in comparison to Vata and Kapha Prakriti . Higher level of cluster of differentiation (CD) 14 markers in Pitta Prakriti , CD25 and CD56 in Kapha Prakriti individuals. Vata Prakriti individuals have “A” blood group, maximum Pitta Prakriti individuals have “O” blood group while maximum Kapha Prakriti individuals have “B” blood group and genotype correlation shows that HLA DRB1 ((human leukocyte antigen, dimer beta chain) gene polymorphism, CYP2C19 (Cytochrome P450 2C19) gene polymorphism and PGM1 (Phosphoglucomutase 1) polymorphism have scientific variations with the human Prakriti concept. Conclusion: Prakriti of individual has strong relation with Hematological parameters (CBC, lipid profile, Liver function test (LFT)), Body mass index (BMI), anthropometry, blood groups and genotypes.

Prevalence of CYP2C19 Gene Polymorphism and Its Influence In Omeprazole Metabolism As Predictors Of Drug Inoxification In Malay Ethnic In South Sumatra

Cytochrome P450 2C19 (CYP2C19) is an enzyme complex that plays a role in the metabolism of several drugs and is part of the super family of cytochrome P450. Genetic polymorphisms in these enzymes are associated with the emergence of poor metabolic phenotypes (poor metabolizers / PMs and intermediate metabolizers / IMs) that have a poor ability to metabolize the drugs that become substrates. Genotypes and phenotypes were analyzed using PCR-RFLP and bio-analysis of omeprazole levels in 30 subjects from ethnic Malay living in South Sumatra. Markers used to assess the presence of polymorphisms in the CYP2C19 gene are two polymorphic sites of exon 5 (CYP2C19 * 2) and exon 4 (CYP2C19 * 3). 321 bp DNA bands for exon 5 and 271 bp for exon 4 will be produced after DNA amplification by PCR method under denaturation for 5 min at 95oC; followed by 60 seconds at 95oC, 60sec at 53oC and 60sec at 72oC for 30 cycles; as well as the final polymerization for 5 minutes at 72 ° C. Furthermore, DNA cutting was done using the restriction enzyme endonuclease SmaI (CYP2C19 * 2) at 30oC and BamHI (CYP2C19 * 3) with incubation at 37oC for 3 hours. Bioanalysis of omeprazole levels in the blood with LC-MS. The results of this study indicate the presence of polymorphisms on both sites will eliminate the enzyme sites SmaI and BamHI. The results showed that 46.7% of South Sumatran Malay populations were classified as PM consisting of 13.3% homozygous mutandan mutant 33.4% heterozygotes. The high phenotype of PM enzyme CYP2C19 in ethnic Malays in South Sumatra predicted to influence metabolism of drugs become substrates. However, based on spearman correlation analysis, the correlation value was 0.035 with p = 0.875. This means that between the CYP2C19 gene polymorphism and the omeprazole levels in the blood there is a weak and meaningless correlation. The results of this study provide an overview of the high genetic polymorphisms of dyspepsia syndrome patients from the Malay population, ie almost half of the study subjects (46.7%). There is a weak and insignificant correlation between polymorphism and omeprazole levels.

CYP2C19 gene polymorphism and platelet responsiveness to clopidogrel in Korean patients with ischemic stroke

Background: The cytochrome P450 2C19(CYP2C19) gene polymorphism plays determinant role in the the metabolism of clopidogrel and influences its antiplatelet effect.

Effect of Cytochrome P450 2C19 681G&gt;A Polymorphism on Premature Coronary Heart Disease

Objective: The aim of our study was to evaluate the association between cytochrome P450 2C19 (CYP2C19) 681G>A polymorphisms and the age of development of coronary heart disease. Additionally, the study might find some biological indicators at the gene level that could help to predict and evaluate the risk of coronary heart disease in time. Methods: This study included 352 individuals with coronary heart disease. Polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) was used to identify CYP2C19 681G>A. The objects were divided into wild type (GG or homozygous CYP2C19*1 wild-type) and mutant type (GA/AA or the mutant CYP2C19*2 allele) on the basis of genotype. The association between CYP2C19 gene polymorphism and the age of onset of coronary heart disease was assessed by multivariate linear regression analysis. Results: There was a significant association in the age of onset between the two groups (t=3.398, P=0.001), which was 58.51±12.72 years in the wild type and 53.95±11.63 years in the mutant group. The frequency of CYP2C19 681A (CYP2C19*2 allele) was 0.32, 0.268, 0.227 in different age groups, which was significantly different (χ 2 =10.745, P=0.005) in different groups, as well as in the genotype. The result, assessed by multiple linear regression, showed that genotype, smoking, obesity, and hyperlipidemia affect the age of onset of coronary heart disease (β was -0.167, 0.156, 0.155, and 0.112, P A gene polymorphism may be one of the risk factors in susceptibility to early onset of coronary heart disease, but not an independent factor because other factors may play a synergistic role.

Roles of CYP2C19 Gene Polymorphisms in Susceptibility to POAG and Individual Differences in Drug Treatment Response.

BackgroundThe aim of this study was to investigate the roles of cytochrome P450 2C19 (CYP2C19) polymorphisms in primary open-angle glaucoma (POAG) susceptibility and individual responses to drug treatment.Material/MethodsThis case-control study consisted of 93 cases with POAG and 125 controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze CYP2C19 single-nucleotide polymorphisms (SNPs). After timolol treatment, patients were classified into side effect (SE) group and non-side effect (NSE) group. According to drug treatment responses, patients were divided into 3 groups: excellent group (Ex) (IOP ≥8 mm Hg); utility group (Ut) (5 <IOP ≤8 mm Hg), and ineffective group (In) (IOP ≤5 mm Hg). Data analysis was performed using SPSS software.ResultsWe found no statistical differences in the alleles and genotypes frequencies of CYP2C19 between the case group and the control group (both P>0.05). Frequencies of extensive metabolizer phenotype and poor metabolizer phenotype or poor metabolizer phenotype and intermediate metabolizer phenotype were significantly different between the SE group and NSE group (both P<0.05). The distribution of intermediate metabolizer phenotype and extensive metabolizer phenotype were significantly different among Ex group, Ut group, and In group (all P<0.05).ConclusionsWe found no evidence that CYP2C19 polymorphisms are associated with susceptibility to POAG. However, different CYP2C19 metabolizer phenotypes were identified and observed to have important effects on the individual differences in drug treatment response.

Quantitative assessment of the influence of cytochrome P450 2C19 gene polymorphisms and digestive tract cancer risk

Cytochrome P450 (CYP) 2C19 metabolizes many promutagens and procarcinogens to biologically active metabolites, which strongly promote proliferation of cancer cells in vitro and in vivo. The CYP2C19 gene exhibits several genetic polymorphisms that are thought to play a major role in inter-individual variability in drug response, drug-xenobiotic interactions, and in cancer susceptibility. Two polymorphisms of the CYP2C19 gene (CYP2C19*2, CYP2C19*3) which was associated with reduced enzyme activity have been investigated extensively digestive tract cancer; however, these studies have yielded contradictory results. To clarify this inconsistency, we performed this meta-analysis including 15 case-control studies with a total of 3,252 cases and 6,269 controls. Overall, we found significant association between CYP2C19*2 and digestive tract cancer (OR = 1.27, 95 % CI, 1.07-1.51, P = 0.007) while no significant results were found for CYP2C19*3. Potential sources of heterogeneity including cancer types, ethnicity, source of control, and sample size of study were assessed. In the subgroup analyses by cancer types, significant association was detected only in esophagus cancer for CYP2C19*2. When stratified by ethnicity, significantly increased risks were found for the CYP2C19*2 polymorphism among Asians. This meta-analysis demonstrated that the CYP2C19*2 polymorphism is a risk factor for developing digestive tract cancer. However, additional very large-scale studies are warranted to provide conclusive evidence on the effects of the CYP2C19 gene on risk of digestive tract cancer.

Association ofCYP2C19*2and*3Genetic Variants with Essential Hypertension in Koreans

PurposeThe cytochrome P450 2C19 (CYP2C19) metabolizes arachidonic acid to produce epoxyicosanoid acids, which are involved in vascular tone and regulation of blood pressure. Recent findings suggest that CYP2C19 gene might be considered as a novel candidate gene for treatment of cardiovascular disease. The aim of the present study was to evaluate the association between two variants, CYP2C19*2 (681G>A) and CYP2C19*3 (636G>A) and the development of essential hypertension (EH) in Koreans.Materials and MethodsWe carried out an association study in a total of 1190 individuals (527 hypertensive subjects and 663 unrelated healthy controls). The CYP2C19 polymorphisms were genotyped using the SNaPShot™ assay.ResultsThe distribution of alleles and genotypes of CYP2C19*3 showed significant difference between hypertensive patients and normal controls (p=0.011 and p=0.013, respectively). Logistic regression analysis indicated that the CYP2C19*3 (636A) allele carriers were significantly associated with EH [odds ratio, 0.691; 95% confidence interval (CI), 0.512-0.932, p=0.016], in comparison to wild type homozygotes (CYP2C19*1/*1). Neither genotype nor allele distribution of CYP2C19*2 polymorphism showed significant differences between hypertensive and control groups (p>0.05).ConclusionOur present findings strengthen the evidence of an association between CYP2C19 gene polymorphism and EH prevalence. In particular, the CYP2C19*3 defective allele may contribute to reduced risk for the development of EH.

Role of cytochrome P450 2C19 genetic polymorphisms in the therapeutic efficacy of omeprazole in Iranian patients with erosive reflux esophagitis.

There are different clinical responses to omeprazole treatment in Iranian patients with gastroesophageal reflux disease. Omeprazole is metabolized in the liver by the cytochrome p450 2c19 (CYP2C19) enzyme. Two common polymorphisms of the CYP2C19 gene affect CYP2C19 enzyme activity. We investigated the effect of CYP2C19 gene polymorphisms on the clinical response to treatment with omeprazole in Iranian patients with erosive reflux esophagitis. Eighty-two Iranian patients with reflux esophagitis were enrolled in the study and underwent treatment with omeprazole at 40 mg daily for 4 weeks. A 2 mL sample of venous blood was obtained from each subject. CYP2C19 genetic polymorphisms were detected using the PCR-RFLP method. The patients were grouped into homo-extensive metabolizers and hetero-extensive metabolizers based on their CYP2C19 polymorphism. The grade of esophagitis was determined via endoscopy. The symptoms score was assessed at the beginning of treatment. Our results showed that the rate of complete clinical response to treatment with omeprazole was 95% in the hetero-extensive metabolizers group, which was higher than in the homo-extensive metabolizers group (P<0.001). CYP2C19 polymorphism influences the therapeutic efficacy of omeprazole in the treatment of Iranian patients with erosive reflux esophagitis. The clinical response and endoscopic healing of esophagitis are both affected by CYP2C19 genotype condition.