Rsa I polymorphism at the cytochrome P4502E1 locus is not related to the risk of alcohol-related severe liver disease

Subclinical atherosclerosis associates with diabetic retinopathy incidence: a prospective study

BACKGROUND

The prospective correlation between subclinical atherosclerosis and diabetic retinopathy (DR) incidence in Chinese patients with type 2 diabetes mellitus (T2DM) remains elusive.

METHODS

Prospective data were obtained from 2781 patients with diabetes, among whom 1,964 and 2,180 T2DM patients without any and referable DR at baseline, respectively, were included in the analysis. Multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

Over a median follow-up of 22.2 months (interquartile range 12.7-27.7), 282 (14.36%) and 125 (5.73%) patients developed any and referable DR, respectively. After adjustment for confounders, each standard deviation (SD) increase in brachial-ankle pulse wave velocity (ba-PWV) was associated with 31% (95% confidence interval 1.15-1.50) and 38% (1.14-1.66) higher risks of incident any and referable DR, respectively. Compared with the lowest ba-PWV quartile, the highest ba-PWV quartile had 135% (1.48-3.72) and 293% (1.83-8.44) higher risks of developing any and referable DR, respectively. Per SD increase of pulse pressure (PP) was associated with 22% (1.09-1.38) and 22% (1.02-1.46) higher risks of incident any and referable DR, respectively. The restricted cubic spline models further indicated a significant linear association of baseline subclinical atherosclerosis with referable DR, and a nonlinear association with any DR. In addition, adding the ba-PWV to the prognostic model for DR incidence improved the C-statistic value, the integrated discrimination improvement value, and the net reclassification improvement value (all P < 0.05).

CONCLUSIONS

Baseline subclinical atherosclerosis was significantly associated with an increased risk of DR incidence, and elevated ba-PWV independently predicted incident DR in T2DM patients.

Genetic Variants of Alcohol Metabolizing Enzymes and Alcohol-Related Liver Cirrhosis Risk

Alcohol-related liver disease (ARLD) is a major public health issue caused by excessive alcohol consumption. ARLD encompasses a wide range of chronic liver lesions, alcohol-related liver cirrhosis being the most severe and harmful state. Variations in the genes encoding the enzymes, which play an active role in ethanol metabolism, might influence alcohol exposure and hence be considered as risk factors of developing cirrhosis. We conducted a case-control study in which 164 alcohol-related liver cirrhosis patients and 272 healthy controls were genotyped for the following functional single nucleotide variations (SNVs): ADH1B gene, rs1229984, rs1041969, rs6413413, and rs2066702; ADH1C gene, rs35385902, rs283413, rs34195308, rs1693482, and rs35719513; CYP2E1 gene, rs3813867. Furthermore, copy number variations (CNVs) for ADH1A, ADH1B, ADH1C, and CYP2E1 genes were analyzed. A significant protective association with the risk of developing alcohol-related liver cirrhosis was observed between the mutant alleles of SNVs ADH1B rs1229984 (P_c value = 0.037) and ADH1C rs283413 (P_c value = 0.037). We identified CNVs in all genes studied, ADH1A gene deletions being more common in alcohol-related liver cirrhosis patients than in control subjects, although the association lost statistical significance after multivariate analyses. Our findings support that susceptibility to alcohol-related liver cirrhosis is related to variations in alcohol metabolism genes.

Roles of cytochrome P4502E1 gene polymorphisms and the risks of alcoholic liver disease: a meta-analysis

Background

Previous studies investigating the association between cytochrome P4502E1 (CYP2E1) polymorphisms and the risk of alcoholic liver diseases (ALD) have yielded conflicting results. Thus, a meta-analysis was performed to clarify the association between CYP2E1 polymorphisms and the risks of ALD.

Methods

A comprehensive literature search was conducted to identify the relevant studies. The fixed or random effect model was selected based on the heterogeneity test among studies. Publication bias was estimated using Begg’s funnel plots and Egger’s regression test.

Results

A total of 27 and 9 studies were finally included for the association between the CYP2E1 Pst I/Rsa I or Dra I polymorphisms and the risks of ALD, respectively. Overall, the combined results showed that homozygous genotype c2c2 was significantly associated with increase risk of ALD in worldwide populations (c2c2 vs. c1c1: OR = 3.12, 95%CI 1.91–5.11) when ALD patients were compared with alcoholics without ALD. Significant associations between CYP2E1 Pst I/Rsa I polymorphism and ALD risk were also observed in Asians (c2c2 vs. c1c1: OR = 4.11, 95%CI 2.32–7.29) and in Caucasians (c2c2/c1c2 vs. c1c1: OR = 1.58, 95%CI 1.04–2.42) when ALD patients were compared with alcoholics without ALD. However, subgroup analysis stratified by ALD types showed that CYP2E1 Pst I/Rsa I polymorphism was not significantly associated with the risks of alcoholic cirrhosis (ALC). No significant association was observed between CYP2E1 Dra I polymorphism and ALD risks.

Conclusion

This meta-analysis suggested that CYP2E1 Pst I/Rsa I polymorphism might be not significantly associated with advanced form of ALD (ALC), but might be significantly associated with other form of ALD such as steatosis, hepatisis, fibrosis. Furthermore, CYP2E1 Dra I polymorphism might be not significantly associated with the ALD risks. Since potential confounders could not be ruled out completely, further studies were needed to confirm these results.

Genetic polymorphisms of genes coding to alcohol-metabolizing enzymes in western Mexicans: association of CYP2E1*c2/CYP2E1*5B allele with cirrhosis and liver function

BACKGROUND

Alcoholic cirrhosis constitutes a major public health problem in the world where ADH1B, ALDH2, and CYP2E1 polymorphisms could be playing an important role. We determined ADH1B*2, ALDH2*2, and CYP2E1*c2 allele frequencies in healthy control individuals (C) and patients with alcoholic cirrhosis (AC) from western Mexico.

METHODS

Ninety C and 41 patients with AC were studied. Genotype and allele frequency were determined through polymerase chain reaction-restriction fragment length polymorphisms.

RESULTS

Polymorphic allele distribution in AC was 1.6%ADH1B*2, 0.0%ALDH2*2, and 19.5%CYP2E1*c2; in C: 6.1%ADH1B*2, 0%ALDH2*2, and 10.6%CYP2E1*c2. CYP2E1*c2 polymorphic allele and c1/c2 genotype frequency were significantly higher (p < 0.05 and p < 0.01, respectively) in patients with AC when compared to C. Patients with AC, carrying the CYP2E1*c2 allele, exhibited more decompensated liver functioning evaluated by total bilirubin and prothrombin time, than c1 allele carrying patients (p < 0.05). Cirrhosis severity, assessed by Child's Pugh score and mortality, was higher in patients carrying the c2 allele, although not statistically significant.

CONCLUSIONS

In this study, CYP2E1*c2 allele was associated with susceptibility to AC; meanwhile, ADH1B*2 and ALDH2*2 alleles were not. CYP2E1*c2 allele was associated with AC severity, which could probably be attributed to the oxidative stress promoted by this polymorphic form. Further studies to clearly establish CYP2E1*c2 clinical relevance in the development of alcohol-induced liver damage and its usefulness as a probable prognostic marker, should be performed. Also, increasing the number of patients and including a control group conformed by alcoholic patients free of liver damage may render more conclusive results. These findings contribute to the understanding of the influence of gene variations in AC development among populations, alcohol metabolism, and pharmacogenetics.

Induction of blood lymphocyte cytochrome P450 2E1 in early stage alcoholic liver cirrhosis

To validate the induction of blood lymphocyte cytochrome P450 2E1 (CYP2E1) expression in alcoholic liver cirrhosis and mRNA and protein expression of CYP2E1 in freshly prepared blood lymphocytes of alcoholic liver cirrhotic (ACP), nonalcoholic cirrhotic patients (NACP), alcoholic controls (ACs), and nonalcoholic controls (NACs) were investigated. Registered ACP and NACP patients at Sanjay Gandhi Postgraduate Institute of Medical Science, Lucknow, India along with NACs and ACs were included in the study. Real time polymerase chain reaction, enzyme-linked immunosorbent assay, and CYP2E1-dependent enzyme activity were determined in blood lymphocytes isolated from cases and controls. Significant increases in CYP2E1 mRNA and protein expression were observed in freshly prepared blood lymphocytes isolated from ACs and ACP patients as compared with respective NACs or NACP patients. A concomitant increase in N-nitrosodimethyamine demethylase activity was evident in the blood lymphocytes of ACs and ACP patients. Interestingly, the comparative increase observed in CYP2E1 expression was of greater magnitude in the blood lymphocytes isolated from ACP patients, although they abstained from alcohol drinking. Findings suggest that significant increase in the CYP2E1 mRNA and protein expression in the blood lymphocytes, isolated from early stage ACP patients, can be used to predict alcohol-induced toxicity.

Polymorphism in cytochrome P450 2E1 and interaction with other genetic risk factors and susceptibility to alcoholic liver cirrhosis

The association of polymorphism in cytochrome P450 2E1 (CYP2E1), the major microsomal ethanol metabolizing enzyme and its interaction with genes, involved in detoxification of reactive oxygen species, such as glutathione-S-transferases M1 (GSTM1) and alcohol intake, gamma-aminobutyric acid receptor gamma2 (GABRG2) was studied with the risk to alcoholic cirrhosis in a case-control study. A total of 160 alcoholic cirrhotic and 125 non-alcoholic cirrhotic cases, visiting the OPD facility of Gastroenterology Department of Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGI), Lucknow, India and 250 non-alcoholic and 100 alcoholic controls having no evidence of liver disease were included in the study. PCR-based RFLP methodology was followed for genotyping studies. Our data revealed that the variant genotypes of CYP2E1 5B exhibited significant association with the alcoholic liver cirrhosis when compared to non-alcoholic controls (OR: 4.3; 95%CI: 1.5-12.4; p: 0.003) or non-alcoholic cirrhosis patients (OR: 5.4; 95%CI: 1.2-24.5; p: 0.01) or alcoholic controls (OR: 4.3; 95%CI: 0.95-19.62; p: 0.04). Haplotype approach revealed that haplotype T-A-T was found to be associated with more than 5-fold increase in risk for alcoholic cirrhosis. Likewise, combination of variant genotype of CYP2E1 5B with null genotype of GSTM1, a phase II detoxification enzyme, resulted in several fold increase in risk in alcoholic cirrhotic patients when compared with non-alcoholic controls or non-alcoholic cirrhotic patients. Further, the combination of variant genotype of CYP2E1 5B with GABRG2, significantly increased the risk upto 6.5-fold in alcoholic cirrhotic patients when compared with non-alcoholic controls thereby suggesting the role of gene-gene interaction in alcoholic cirrhosis.

Association of alcohol-metabolizing genes with alcoholism in a Mexican Indian (Otomi) population

Association studies provide a powerful approach to link DNA variants and genetic predisposition to complex diseases. In this study, we determined the genotype and allelic frequencies of genes encoding enzymes involved in alcohol metabolism in alcoholic and nonalcoholic subjects of related ethnicity. A total of 118 individuals of Otomi Mexican Indian ancestry were included. Fifty-nine were chronic alcoholics according to WHO criteria and alcohol dependents according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV) criteria. They were compared to 59 teetotalers or alcohol consumers of <10 g per day. The restriction fragment length polymorphisms analyzed were ADH1B/MaeIII, ALDH2/MboII, CYP2E1/DraI, CYP2E1/RsaI, and CYP2E1/TaqI. Of the studied polymorphisms, a significant difference between alcoholic and nonalcoholic Otomies was observed only in the CYP2E1/TaqI. The common genotype in alcoholics was A1/A2 (54%), and in nonalcoholics the homozygous A2/A2 (63%) (odds ratio [OR]: 0.28; 95% confidence interval [CI]: 0.13-0.60; P=.002). The frequency of the mutant allele A1 was significantly higher in alcoholics than in nonalcoholics (41 vs. 21%; OR: 2.4; 95% CI: 1.3-4.3; P=.003). This documents the presence of a polymorphism of CYP2E1 that is overexpressed in alcoholic Otomies, in which the variant allele (A1 of CYP2E1/TaqI) is associated with increased susceptibility to alcoholism. The appreciation that this finding may be an additional factor contributing to the high frequency of liver cirrhosis in Otomies requires further investigation.

[Genetic susceptibility to the development of acute alcoholic hepatitis: role of genetic mutations in dehydrogenase alcohol, aldehyde dehydrogenase and cytochrome P450 2E1]

OBJECTIVE

Analyze the frequencies of genetic mutation in alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH) and cytochrome P450 2E1 (CYP2E1) and establish their possible association with the development of acute alcoholic hepatitis (AAH).

METHODOLOGY

Case-control study in a total of 85 Spanish patients. We distinguish three groups (one case group and two control groups) based on hepatic histological lesion and alcohol consumption: controls (group 1: teetotalers; group 2: drinkers without AAH; cases: group 3: drinkers with AAH). Case diagnosis was established based on the presence of polymorphonuclear leukocyte infiltrate in histological study. We analyzed the presence of the genetic mutations R47H and R369C (ADH2), E487K (ALDH2) and mutation Rsa I of CYP2E1 (allele c2) by polymerase chain reaction (PCR) and capillary electrophoresis.

RESULTS

The allele c2 of CYP2E1 was found in 10%, 16% and 50% of the groups 1, 2 and 3 patients, respectively. Presence of the mutation Rsa I showed influence on the development of AAH (odds ratio [OR]: 3.63; confidence interval (95% [CI]: 0.88-15.02).

CONCLUSIONS

The data suggest a possible association between the presence of the Rsa I of CYP2E1 and the development of AAH in patients with chronic alcohol consumption.

Do alcohol-metabolizing enzyme gene polymorphisms increase the risk of alcoholism and alcoholic liver disease?

Case-control studies that have investigated the association between alcoholism and alcohol-induced liver damage and the ADH2, ADH3, CYP2E1, and ADLH2 polymorphisms have reported controversial or inconclusive results. Thus, we conducted a meta-analysis of 50 association studies of the above polymorphisms. We explored potential sources of heterogeneity and bias, performed subgroup analyses by racial background and sex, performed sensitivity analyses for studies not in Hardy-Weinberg equilibrium, and performed a subgroup analysis for cases that met strict criteria for alcoholism. The present meta-analysis underscores significant associations of ADH2*1, ADH3*2, and ALDH2*1 alleles and the risk of alcoholism (OR = 1.89 [95% CI 1.56-2.28], 1.32 [95% CI 1.12-1.57], and 4.35 [95% CI 3.04-6.23], respectively). The subsequent subgroup analyses showed association for ADH2*1 and ADH3*2 only in East Asians (OR = 2.23 [95% CI 1.81-2.74] and 1.91 [95% CI 1.45-2.53], respectively) and East Asian males (OR = 2.21 [95% CI 1.57-3.10], 1.69 [95% CI 1.10-2.59], respectively). In East Asian males, the OR for ALDH2*1 was 3.66 (95% CI 1.68-7.96). In Caucasians, sensitivity analysis revealed an association for ADH2*1 in alcoholism (OR = 1.62 [95% CI 1.22-1.89]). When strict criteria were imposed, the pattern of results remained unaltered. For liver disease, there were no significant associations for ADH2*1, ADH3*2, or ALDH2*1 in all subpopulations. The CYP2E1 polymorphism showed no association whatsoever. There is evidence that alleles are mainly dominant. In conclusion, there was heterogeneity between studies in alcoholism for ADH2, ADH3, and ALDH2, and lack of bias in all polymorphisms. The above findings reinforce the need for more rigorous studies, and for regular synthesis of studies' results.

Relationship between genetic polymorphism of cytochrome P450IIE1 and fatty liver

AIM: To study the correlation between genetic polymorphism of cytochrome P450IIE1 (CYPIIE1) and fatty liver.

METHODS: Peripheral blood mononuclear cells were collected in 56 patients with fatty liver, 26 patients without fatty liver and 20 normal controls. Then PCR-RFLP was used to analyze genetic polymorphism of CYPIIE1 in monocytes on the region of Pst I and Rsa I.

RESULTS: The frequency of homozygotic C1 gene in patients with alcoholic fatty liver (28.6%), obese fatty liver (38.5%), or diabetic fatty liver (33.3%) was significantly lower than that of the corresponding patients without fatty liver (100%, 100% and 80% respectively), while the frequency of C2 genes, including C1/C2 and C2/C2, was significantly higher (71.4%/0%, 61.5%/0%, and 66.7%/20%) (P < 0.01). The frequency distribution of the above genes of non-fatty liver patients (100%/0, 100%/0, and 80%/20%) was not significantly different from that of the normal controls (85%/15%) (P > 0.05).

CONCLUSION: The genetic polymorphism of CYPIIE1 on the position of Pst I and Rsa I is related to the susceptibility of fatty liver. Besides, C2 gene may play a key role in the pathogenesis of fatty liver.

Polymorphism of the 5'-flanking region of the CYP2E1 gene: an association study with alcoholism

BACKGROUND

Recently, a restriction fragment length polymorphism in the regulatory region of the CYP2E1 gene was identified. It has been suggested that the polymorphism is associated with the elevated activity of the cytochrome P-450 2E1 (CYP2E1) enzyme in obese or alcoholic subjects. However, significance of the polymorphism in connection with alcoholism has not been studied. In the present study, we have characterized these repeated sequences in the 5'-untranslated region of the CYP2E1 gene in Japanese subjects and North American white subjects and investigated whether these polymorphisms are associated with drinking habits and alcoholism.

METHODS

DNAs were isolated from blood samples of 192 Japanese nonalcoholics and 202 alcoholics as well as 125 North American white nonalcoholics. DNA samples were amplified by polymerase chain reaction and subjected to a fluorescent-based single-strand conformational change polymorphism analysis, DNA fragment analysis, and polymerase chain reaction-direct sequencing.

RESULTS

Four alleles (A1-A4) were found, which were differentiated by the six subunits (L1, L2, L3, L4, S1, S2) based on the size difference and nucleotide replacement. A2 and A4 alleles were observed in the two ethnic groups (A2: Japanese subjects, 0.752; white subjects, 0.976; A4: Japanese subjects, 0.227; white subjects, 0.016). However, A1 allele was found only in North American white subjects (0.008), and A3 allele was detected only in Japanese subjects (0.021). Allele frequencies were significantly different between the two ethnic groups (p < 0.0001). Distribution of genotypes between Japanese nonalcoholics and alcoholics were not significantly different. Also, no significant difference for the allele frequencies was observed between Japanese moderate drinkers and heavy drinkers.

CONCLUSIONS

Our data suggested no association among the polymorphic repeats, drinking behavior, and alcoholism. Allele frequencies were significantly different between Japanese subjects and North American white subjects.

Genetic polymorphisms of cytochrome p4502E1 and susceptibility to alcoholic liver disease and hepatocellular carcinoma in a white population: a study and literature review, including meta-analysis

AIMS

To investigate the associations between the Rsa I, Dra I, and Taq I genetic polymorphisms of cytochrome p4502E1 and susceptibility to alcoholic liver disease or to hepatocellular carcinoma.

METHODS

DNA samples isolated from 61 patients with alcoholic liver disease, 46 patients with hepatocellular carcinoma, and 375 healthy controls were subjected to polymerase chain reaction amplification followed by digestion with the endonucleases Rsa I, Dra I, or Taq I. Meta-analysis was performed using data from previous studies of Rsa I polymorphism and the risk of alcoholic liver disease.

RESULTS

No association was found between any of the three polymorphisms and susceptibility to hepatocellular carcinoma. The distributions of Rsa I and Dra I alleles among the patients with alcoholic liver disease were not significantly different from those among the control group. Meta-analysis of this data and previous data concerning Rsa I polymorphism and alcoholic liver disease risk failed to demonstrate any significant association between the two. However, the alcoholic liver disease group in this study showed a significantly lower frequency of the less common Taq I allele compared with the healthy control group (odds ratio, 0.33; 95% confidence interval, 0.12 to 0.78).

CONCLUSIONS

Possession of the less common Taq I cytochrome p4502E1 allele is associated with reduced susceptibility to alcoholic liver disease. There is no existing evidence that the Taq I polymorphism is directly associated with altered alcohol metabolism, but it might be in linkage disequilibrium with as yet unidentified protective factors.

Mutations in the exons and exon-intron junction regions of human cytochrome P-4502E1 gene and alcoholism

Cytochrome P-4502E1 (CYP2E1) is a major component of the microsomal ethanol-oxidizing system (MEOS) and is also involved in the metabolism of a variety of foreign compounds, including carcinogens. It has been shown that there are interindividual variations in the expression of human CYP2E1. Gene-environmental interactions have been suggested to account for the difference. In this study, we screened nine exons and exon-intron junctions of the human CYP2E1 gene for detecting allelic variants in genomic DNA samples obtained from 115 Japanese controls, 96 alcoholics, and 44 patients with alcoholic liver diseases. A novel missense mutation in exon 2 (V72L) was found in Japanese controls, but the frequency was low (2.6%). In addition, two novel silent mutations (T303T and F420F), together with one mutation in intron 2, were found. However, no association of these mutations with alcoholism and alcoholic liver diseases was found. Our data indicate that nucleotide replacement in the open reading frame of CYP2E1 gene is not a major factor for interindividual differences in expression of CYP2E1 and susceptibility to alcohol-related disorders.

The inheritance of alcoholic liver disease

Available evidence supports the concept that alcoholic liver disease (ALD) is a multifactorial disease with a heritable component. A number of polymorphic genes with small and additive effects will thus encode susceptibilty to this 'polygenic' disease. Molecular genetic studies of ALD are in their infancy, and methods available for the genetic dissection of complex traits are discussed. Some candidate genes have been identified, and studies have been undertaken to test for association between specific alleles and ALD susceptibility. There is evidence to support a role for alleles of two genes encoding enzymes involved in the oxidative metabolism of alcohol (acetaldehyde dehydrogenase2*2 and cytochrome P4502E1 c2 allele) in susceptibility to ALD. More recently, attention has focused on cytokines, and there are now data showing association of specific alleles of both tumour necrosis factor alpha and interleukin-10 with predisposition to ALD. These candidate genes need to be subjected to rigorous evaluation in different populations. Such research should help to define more precisely the molecular mechanisms underlying the development of ALD in a sub-population (< 20%) of alcoholics, thereby improving the hepatologist's ability to develop rational treatments.

CYP2E1 activity in patients with alcoholic liver disease

BACKGROUND/AIMS

In addition to the possible toxicological impact of cytochrome P4502E1 (CYP2E1) in alcohol-induced liver damage, its activity can be regarded as a variable for drug action in patients with alcoholic liver disease as CYP2E1 is involved in the metabolism of several drugs, for example, paracetamol and halogenated anesthetics. The purpose of our study was to acquire detailed knowledge of CYP2E1 activity in patients with progressingly severe manifestations of alcoholic liver disease.

METHODS

The concentration ratio of 6-hydroxy-chlorzoxazone/chlorzoxazone in plasma 2 h after ingestion of 500 mg chlorzoxazone (so-called metabolic ratio) has been shown to reflect CYP2E1 activity in vivo. We examined CYP2E1 activity in 56 Caucasian inpatients with minor (n=20), more pronounced (n=14) and severe alcoholic liver disease (n=22). Alcohol abusers were compared to healthy teetotallers (n=14).

RESULTS

Metabolic ratios were increased 3-fold in actively drinking (ethanol-induced) compared to abstaining (non-induced) patients with alcoholic liver disease (1.19+/-0.84 vs. 0.44+/-0.45, mean+/-SD, (p<0.0001). CYP2E1 activity was significantly lower in non-induced patients with severe alcoholic liver disease (0.19+/-0.10) than in healthy controls (0.50+/-0.28, p<0.01), abstaining alcohol abusers with minor (0.67+/-0.60, p<0.01) and more pronounced alcoholic liver disease (0.53+/-0.31, p<0.01). When non-induced patients with alcoholic liver disease were arranged in progressing order of liver damage (minor, more pronounced, severe alcoholic liver disease), there was a significant decline in CYP2E1 activity (p=0.0008).

CONCLUSIONS

In non-induced patients, CYP2E1 activity decreases in line with severity of alcoholic liver disease. CYP2E1-mediated drug metabolism is significantly impaired in severe alcoholic liver disease.