Genetic polymorphism analysis of cytochrome P4502E1 (CYP2E1) in a Chinese Tibetan population

Association between CYP2E1 polymorphisms and colorectal cancer risk: a systematic review and meta-analysis

CYP2E1 encodes an enzyme that participates in the activation of several carcinogenic substances. Thus, numerous studies have investigated the association between CYP2E1 polymorphisms and colorectal cancer (CRC) risk, but inconclusive results have been obtained. We performed a meta-analysis to precisely evaluate the relationship of CYP2E1 rs2031920, rs3813867, and rs6413432 polymorphisms with the susceptibility to CRC. Scopus, Web of Science and PubMed databases were searched to identify eligible studies, and the association between the polymorphisms and CRC risk was then quantitatively synthesized using different genetic models. Eighteen studies with 23,598 subjects were selected for inclusion into the analysis. Significant association between rs2031920 and an increased CRC risk was observed in homozygous (OR = 1.496, 95% CI 1.177-1.901, P = 0.001), recessive (OR = 1.467, 95% CI  1.160-1.857, P = 0.001) and allele (OR = 1.162, 95% CI  1.001-1.349, P = 0.048) models. Significant association was not found for rs3813867 and rs6413432 (P > 0.05). In conclusion, our results suggest that rs2031920, but not rs3813867 and rs6413432, is associated with the risk of CRC.

Selection pressure at altitude for genes related to alcohol metabolism: A role for endogenous enteric ethanol synthesis?

NEW FINDINGS

What is the topic of this review? Highland natives have undergone natural selection for genetic variants advantageous in adaptation to the hypobaric hypoxia experienced at high altitude. Why genes related to alcohol metabolism appear consistently selected for has not been greatly considered. We hypothesize that altitude-related changes in the gut microbiome offer one possible explanation. What advances does it highlight? Low intestinal oxygen tension might favour the production of ethanol through anaerobic fermentation by the gut microbiome. Subsequent increases in endogenous ethanol absorption could therefore provide a selection pressure for gene variants favouring its increased degradation, or perhaps reduced degradation if endogenously synthesized ethanol acts as a metabolic signalling molecule.

ABSTRACT

Reduced tissue availability of oxygen results from ascent to high altitude, where atmospheric pressure, and thus the partial pressure of inspired oxygen, fall (hypobaric hypoxia). In humans, adaptation to such hypoxia is necessary for survival. These functional changes remain incompletely characterized, although metabolic adaptation (rather than simple increases in convective oxygen delivery) appears to play a fundamental role. Those populations that have remained native to high altitude have undergone natural selection for genetic variants associated with advantageous phenotypic traits. Interestingly, a consistent genetic signal has implicated alcohol metabolism in the human adaptive response to hypobaric hypoxia. The reasons for this remain unclear. One possibility is that increased alcohol synthesis occurs through fermentation by gut bacteria in response to enteric hypoxia. There is growing evidence that anaerobes capable of producing ethanol become increasingly prevalent with high-altitude exposure. We hypothesize that: (1) ascent to high altitude renders the gut luminal environment increasingly hypoxic, favouring (2) an increase in the population of enteric fermenting anaerobes, hence (3) the synthesis of alcohol which, through systemic absorption, leads to (4) selection pressure on genes relating to alcohol metabolism. In theory, alcohol could be viewed as a toxic product, leading to selection of gene variants favouring its metabolism. On the contrary, alcohol is a metabolic substrate that might be beneficial. This mechanism could also account for some of the interindividual differences of lowlanders in acclimatization to altitude. Future research should be aimed at determining any shifts to favour ethanol-producing anaerobes after ascent to altitude.

Effects of Sodium Valproate Monotherapy on Blood Liver Enzyme Levels in Patients with Epilepsy: A Meta-Analysis

We conducted this meta-analysis to assess the effects of sodium valproate (VPA) monotherapy on blood liver enzymes in patients with epilepsy. PubMed, Web of Science, EBSCO, Cochrane Library, Wanfang, China national knowledge infrastructure databases were searched. Nine studies were included. Results showed: (1) The overall SMD for blood AST, ALT, and GGT levels of VPA monotherapy group versus control group were 0.70 (95% CI=0.31 to 1.09, Z=3.52, p=0.0004), 0.47 (95% CI=- 0.01 to 0.95, Z=1.91, p=0.06), 0.44 (95% CI=0.29 to 0.60, Z=5.55, p<0.00001), respectively. (2) In subgroup meta-analysis, increased blood AST and GGT levels were observed in epileptic minors (AST: total SMD=0.85, 95% CI=0.40 to 1.30, Z=3.69, p=0.0002; GGT: total SMD=0.46, 95% CI=0.29 to 0.63, Z=5.25, p<0.00001). Elevated blood ALT level was observed in Asian patients receiving VPA monotherapy (total SMD=0.70, 95% CI=0.51 to 0.90, Z=7.01, p<0.00001), and the early stage of VPA monotherapy (total SMD=0.93, 95% CI=0.57 to 1.29, Z=5.09, p<0.00001). Overall, our results indicated that blood AST and GGT were significantly increased in epileptic minors receiving VPA monotherapy. The elevation of blood ALT was observed in Asian patients and the early stage of VPA monotherapy. However, due to the small number of included studies, our results should be considered with caution.

CYP2E1, GSTM1, and GSTT1 genetic polymorphisms and their associations with susceptibility to antituberculosis drug-induced liver injury in Thai tuberculosis patients

Antituberculosis drug-induced liver injury (ATDILI) is the common adverse reaction of antituberculosis drugs. Glutathione S-transferases (GSTs), which are phase II metabolizing enzymes for detoxification, are recognized as potential mediators of hepatotoxicity. However, role of GSTs polymorphisms in ATDILI pathogenesis has never been observed in Thais. This study aimed to investigate associations between GSTs and ATDILI susceptibility. This retrospective case-control multicentered study was conducted by the collaboration from ten secondary and tertiary care hospitals across Thailand, including Northern, Central, and Southern parts of Thailand. We enrolled 80 tuberculosis (TB) patients with ATDILI and 174 those without ATDILI into the study. Polymerase chain reaction (PCR) was used to determine genetic polymorphisms of GSTM1 and GSTT1 genes. CYP2E1 genotyping data were derived from microarray data. We illustrated that GSTT1 null and GSTM1/GSTT1 dual null genotypes were correlated with an increased risk of ATDILI with odds ratio (OR) at 1.83 (95% confidence interval (CI), 1.00 to 3.35; P = 0.049) and 2.12 (95%CI, 1.02 to 4.38; P = 0.044), respectively. Interestingly, GSTT1 null and GSTM1/GSTT1 dual null genotypes were found to be correlated with an increased risk of ATDILI in Thai TB patients who carried CYP2E1 wild type phenotype with OR 2.99 (95%CI, 1.07 to 8.39; P = 0.037) and 3.44 (95%CI, 1.01 to 11.71; P = 0.048), respectively. Collectively, GSTT1 null and GSTM1/GSTT1 dual null genotypes were associated with a higher risk of ATDILI in Thai TB patients, which may serve as alternative genetic biomarkers for ATDILI.

Genetic variation of pharmacogenomic VIP variants in Zhuang nationality of southern China

Drug gene polymorphisms are strongly associated with disease. Previous studies have shown that the frequency of drug genes varies in different populations. At present, there are no reports about the polymorphism of the drug genome in the Zhuang population in southern China. This study conducted a pharmacogenomics study on the Zhuang population in southern China. Therefore, we conducted genotyping on 105 Zhuang samples, and compared the genotyping results with those of other 11 ethnic groups after statistical analysis. Our results show that, compared with the 11 populations in the HapMap data set, the differences between the CYP2E1 rs2070676 and CYP2D6 rs1065852 of the Zhuang nationality are the largest. This study fills in the blank of the drug genome information of the Zhuang nationality in southern China. The two sites of Rs2070676 (CYP2E1) and rs1065852 (CYP2D6) provide a reliable basis for the prediction of the efficacy of certain drugs. Its main purpose is to provide theoretical basis for safe drug use in the Zhuang region of southern China.

CYP17A1 Polymorphisms Are Linked to the Risk of Coronary Heart Disease in a Case-Control Study

BACKGROUND

Cytochrome P450 17A1 (CYP17A1) catalyzes the formation and metabolism of steroid hormones and is required for cortisol and androgens. There is increasing evidence that CYP17A1 plays an important role in the development of coronary heart disease (CHD). However, the association of CYP17A1 polymorphisms and CHD susceptibility is still not clear.

METHODS

We conducted a case-control study with 396 CHD cases and 461 healthy controls from Hainan province, China. Using the Agena MassARRAY platform, we genotyped 4 genetic variants (rs3740397, rs1004467, rs4919687, and rs3781286) in CYP17A1. Logistic regression analysis was used to assess the association of CYP17A1 polymorphisms with CHD risk by odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

It showed that A allele of CYP17A1 rs4919687 carried with a 1.59-fold increased risk of CHD (OR = 1.59; 95% CI = 1.26-1.99; P < 0.001). Also, rs4919687 was significantly associated with CHD risk under various models (homozygote: OR = 3.60; 95% CI = 1.64-7.83; P = 0.001; dominant: OR = 1.51; 95% CI = 1.06-2.13; P = 0.021; recessive: OR = 3.28; 95% CI = 1.51-7.14; P = 0.003; additive: OR = 1.56; 95% CI = 1.17-2.07; P = 0.002). Moreover, analysis showed that Ars1004467 Ars4919687 haplotype was a protective factor of CHD (OR = 0.64; 95% CI = 0.48-0.86; P = 0.002).

CONCLUSIONS

Our study suggests that CYP17A1 polymorphisms are associated with CHD susceptibility in the Hainan Han Chinese population.

Genetic polymorphism in cytochrome P450 2E1 and alcoholic pancreatitis sus-ceptibility: a meta-analysis

BACKGROUND

The association between cytochrome P450 2E1 (CYP2E1) polymorphism and the risk of alcoholic pancreatitis is contentious. This meta-analysis aimed to demonstrate the association between CYP2E1 RsaI/PstI, or DraI polymorphisms and the susceptibility of alcoholic pancreatitis.

MATERIALS AND METHODS

We searched for sources and background in Pubmed, Medline, Web of science and CNKI (Chinese national knowledge infrastructure), using the following keywords: "cytochrome P450 2E1" or "CYP2E1", "polymorphism" or "genotype", in combination with "alcoholic pancreatitis". All meta-analyses were performed with Stata 12.0. Subgroup analyses on ethnicity and type of alcoholic pancreatitis were conducted as well.   Results: Eleven articles, which met the inclusion criteria, included 595 patients with alcoholic pancreatitis, and 1767 controls. For the general population, our analysis suggested no obvious association between CYP2E1 RsaI/PstI or DraI polymorphisms and the risk of alcoholic pancreatitis. However, in the non-Asian subgroup, significant associations were found between the risk for alcoholic pancreatitis and CYP2E1 RsaI/PstI polymorphism [dominant model: odds ratio (OR) =1.92, 95 % confidence interval (CI): 1.25-2.95, p =0.003; allelic contrast model: OR =1.99, 95 % CI: 1.35-2.92, p <0.001. There was not a significant association found within the Asian group. Meanwhile, the susceptibilities of chronic alcoholic pancreatitis were significantly increased for dominant and allelic contrast models of CYP2E1 RsaI/PstI polymorphism [OR =1.62, 95 % CI: 1.12-2.34; p =0.011; OR =1.62, 95 % CI: 1.17-2.24, p = 0.004, respectively] but not for acute alcoholic pancreatitis for all population.

CONCLUSIONS

CYP2E1 RsaI/PstI polymorphism may increase the risk of alcoholic pancreatitis in the non-Asian population. Additionally, the CYP2E1 RsaI/PstI polymorphism may increase the susceptibility for chronic alcoholic pancreatitis for all population. HIPPOKRATIA 2018, 22(2): 60-67.