微粒体环氧化酶与谷胱甘肽S转移酶的遗传多态性对新生儿出生体重的影响

「目的」探讨母亲微粒体环氧化酶（ＥＰＨＸ１）与谷胱甘肽Ｓ转移酶（ＧＳＴＭ１，ＧＳＴＴ１）的遗传多态笥对新生儿出生体重的影响。「方法」采用回顾性流行病学调查方法，使用统一调查表，由经过培训的调查员在北京燕山某医院对入院分娩的６３０个母亲婴儿对进行调查。「结果」单因素分析发现：ＥＰＨＸ１和ＧＳＴＴ１、ＧＳＴＭ１基因多态对新生儿出生体重的影响无显著意义。经母亲年龄、文化程度、生育史、芳香烃溶剂暴露、在家     

Polymorphisms in glutathione-related genes affect methylmercury retention

Methylmercury is eliminated from the human body as glutathione (GSH) conjugates. GSH production is mediated by glutamyl-cysteine ligase (GCL) and conjugation by glutathione S-transferases (GST). In this study, the authors tested whether polymorphisms in GCL and GST genes modify methylmercury retention. Erythrocyte mercury concentration (EryHg), plasma polyunsaturated fatty acids (PPUFA), and genotype for GCLC, GCLM, GSTA1, GSTM1, GSTP1, and GSTT1 were determined in 365 individuals. A general linear model was developed for analyzing whether genotype modified the regression of EryHg on PPUFA. The presence of one variant allele for either GCLC-129 or GSTP1-114 was associated with higher EryHg and steeper regression slope. No similar trends were shown for GCLM, GSTA1, GSTM1, or GSTT1. These findings indicate that GCLC polymorphisms that affect GSH production also affect methylmercury retention, and that GSTP1 may play a role in conjugating methylmercury with GSH.     

Glutathione S-transferase polymorphisms and colorectal cancer: a HuGE review

The genes glutathione S-transferase M1 (GSTM1) (chromosome 1p13.3) and glutathione S-transferase T1 (GSTT1) (22q11.2) code for cytosolic enzymes glutathione S-transferase (GST)-mu and GST-theta, respectively, which are involved in phase 2 metabolism. Both genes may be deleted. There is geographic and ethnic variation in genotype frequencies for both genes. In developed countries, colorectal cancer is the second most common cancer. Colorectal cancer has been inconsistently associated with polycyclic aromatic hydrocarbons in diet and tobacco. Because GST enzymes are involved in polycyclic aromatic hydrocarbon metabolism, it has been postulated that genotype may modify colorectal cancer risk associated with polycyclic aromatic hydrocarbon exposure. No consistent associations between GSTM1 or GSTT1 genotype and colorectal cancer have been observed. However, most studies have methodological limitations. Few have investigated gene-environment interactions. No interactions between GSTM1 or GSTT1 genotype and smoking and colorectal cancer risk have been reported. One polyp study suggests an interaction between GSTM1 genotype and smoking. Two studies suggest increased disease risk in subjects with high meat intake and GST nonnull genotype, contrary to the underlying hypothesis. One study suggests a strong inverse relation between colorectal adenomas and broccoli consumption, particularly in subjects who are GSTM1 null. These finding require confirmation. Methods for determining GSTM1 and GSTT1 genotype are well established. Population testing is not currently justified.     

GST Polymorphisms Interact With Dietary Factors to Modulate Lung Cancer Risk: Study in a High-Incidence Area

The aim of this study was to explore possible correlations between glutathione S-transferases (GST) polymorphisms, smoking, diet, and lung cancer susceptibility in a rural Spanish region with one of the highest incidence rates of the country. All lung cancer patients living in the area (103) and 247 matched controls were genotyped for the GST mu 1 (GSTM1) null, GST theta 1 (GSTT1) null, and GST pi 1 (GSTP1) Isoleucine (Ile) 105 valine (Val) polymorphisms and interviewed to gather information on smoking and dietary habits. Neither the presence of GST polymorphisms nor their interaction with smoking was independently associated to lung cancer risk. The intake of carotenoid-rich red and yellow vegetables was inversely associated with lung cancer (P < 0.05). Interestingly, this was observed only in carriers of the GSTM1 (P = 0.04), GSTT1 (P = 0.03), or GSTM1/T1 (P = 0.04) positive genotypes. Similarly, the consumption of citrus fruits was more frequent among cancer-free subjects who carried functional GSTM1 (P = 0.04) or both GSTM1 and GSTT1 enzymes (P = 0.04). The results show that the inverse association observed between the intake of dietary carotenoid-rich vegetables and lung cancer risk is dependent on the GST genotype. These results warrant further investigations to confirm the observed associations.     

脐血中谷胱甘肽s转移酶基因多态性与维汉新生儿低出生体重的关系

目的探讨乌鲁木齐市维吾尔族与汉族新生儿脐带血中谷胱甘肽s转移酶(GST)M1与T1基因多态性与低出生体重的关系。方法采用1∶3病例对照研究方法,收集新生儿脐带血并提取DNA,采用多重等位基因特异聚合酶链反应(PCR)方法分析GSTM1和GSTT1基因多态性。结果GSTM1缺失基因型为60.5%,GSTT1缺失基因型为5%,同时具有GSTM1和GSTT1缺失基因型的频率为3.5%。正常出生体重新生儿脐血中GSTT1基因型缺失的频率与低出生体重儿之间差异有统计学意义(P0.05)。GSTT1基因型缺失的频率在维吾尔族正常与低出生体重新生儿间差异有统计学意义(P0.05)。维吾尔族正常出生体重与低出生体重新生儿间各组合基因型频率构成比分布差异有统计学意义(P0.05)。结论脐血中GSTT1基因型缺失可能会增加新生儿低出生体重的发生,也会增加维吾尔族新生儿低出生体重的发生。而脐血中GSTM1基因型缺失可能不会影响新生儿低出生体重的发生。维吾尔族不同出生体重新生儿间各组合基因型频率构成比分布有差异。因此应全面了解低出生体重发生的原因,从而提高新生儿的出生质量。     

The role of polymorphisms of glutathione S-transferases GSTM1, M3, P1, T1 and A1 in susceptibility to alcoholic liver disease

AIMS AND METHODS: Oxidant stress is proposed to be an important pathogenic factor in liver damage related to alcohol. The glutathione S-transferases (GSTs) are a group of polymorphic enzymes that are important in protection against oxidant stress. As there is evidence for genetic susceptibility to alcohol-related liver disease we have compared the frequency of polymorphisms of GSTM1, M3, P1, T1 and A1 by polymerase chain reaction (PCR) on leucocyte DNA in patients from North Staffordshire, Birmingham and Liverpool with alcohol-related chronic liver disease heavy drinking and normal local controls. RESULTS: There were no significant differences in GSTM1, GSTM3 or GSTP1 genotype frequencies among patients, drinking and non-drinking controls from the three centres. There was a significant increase in the GSTT1 null Liverpool alcoholic liver disease (ALD) patients compared with corresponding non-drinking controls (26.3 and 14.6%, respectively; P = 0.044, odds ratio (OR) = 2.1, 95% CI = 1.1-4.7) though this was not repeated in the Birmingham and North Staffordshire cohorts. For GSTA1, the -69 CC genotype was associated with increased risk of ALD in the Liverpool group, but a reduced risk in the North Staffordshire group. CONCLUSIONS: We have failed to demonstrate within the limitation of a case-control study a reproducible significant association of GST polymorphisms with susceptibility to ALD but there are suggestions that GSTA1 and GSTT1 warrant further study.     

GSTT1 genotype modifies the association between cruciferous vegetable intake and the risk of myocardial infarction

BACKGROUND: Cruciferous vegetables are a major dietary source of isothiocyanates that may protect against coronary heart disease. Isothiocyanates induce glutathione S-transferases (GSTs), polymorphic genes that code for enzymes that conjugate isothiocyanates, as well as mutagens and reactive oxygen species, to make them more readily excretable. OBJECTIVE: The objective of the study was to determine whether GST genotypes modify the association between cruciferous vegetable intake and the risk of myocardial infarction (MI). DESIGN: Cases (n = 2042) with a first acute nonfatal MI and population-based controls (n = 2042) living in Costa Rica, who were matched for age, sex, and area of residence, were genotyped for a deletion polymorphism in GSTM1 and GSTT1 and an Ile105Val substitution in GSTP1. Cruciferous vegetable intake and smoking status were determined by questionnaire. Odds ratios (ORs) and 95% CIs for MI were estimated by unconditional logistic regression. RESULTS: Compared with the lowest tertile of cruciferous vegetable intake, the highest tertile was associated with a lower risk of MI among persons with the functional GSTT1*1 allele (OR: 0.70; 95% CI: 0.58, 0.84) but not among those with the GSTT1*0*0 genotype (OR: 1.23; 95% CI: 0.83, 1.82) (P = 0.006 for interaction). This protective effect among those with the GSTT1*1 allele was greater for current smokers (OR: 0.54; 95% CI: 0.36, 0.79) than for nonsmokers. GSTP1 and GSTM1 did not modify the association between cruciferous vegetable intake and MI. CONCLUSIONS: Consumption of cruciferous vegetables was associated with a lower risk of MI among those with a functional GSTT1*1 allele, which suggests that compounds that are detoxified by this enzyme contribute to the risk of MI.     

The role of glutathione S-transferase M1 and T1 gene polymorphisms and fruit and vegetable consumption in antioxidant parameters in healthy subjects

The correlation of glutathione S-transferase (GST) M1/T1 genetic polymorphisms with oxidative stress-related chronic diseases was proved recently. The aim of the present study was to investigate the association of GSTM1/T1 genetic polymorphisms with antioxidant biomarkers and consumption of fruits and vegetables (F&V) in healthy subjects. In this study, for conducting a 3 d dietary survey, 190 healthy adults were recruited. After DNA extraction, a multiple PCR method was used for GSTM1/T1 genotyping. A spectrophotometer method was applied for the determination of plasma total antioxidant capacity (T-AOC), vitamin C level and erythrocyte GST enzyme activity. A general linear model was used to compare the mean values of antioxidant parameters for different GSTM1/T1 genotypes and consumption of F&V. Polymorphisms of GSTM1/T1 had no effects on plasma T-AOC and vitamin C levels. Deletion of the GSTM1 gene decreased the erythrocyte GST activity. There was correlation between plasma T-AOC and consumption of F&V in the GSTM1? or GSTT1? subjects. A similar pattern was evident for erythrocyte GST activity in the GSTM1? subjects. No association was found among consumption of F&V and GSTM1/T1 genotypes and plasma vitamin C level. Different consumption of F&V had no impact on plasma T-AOC and vitamin C levels in the GSTM1?/GSTT1? or GSTM1?/GSTT1? subjects. The erythrocyte GST activity was more sensitive to consumption of F&V in the individuals with the GSTM1?/GSTT1? genotype. Association was found among GSTM1/T1 genotypes, antioxidant parameters and consumption of F&V. Large-scale and multiple ethnic studies are needed to further evaluate the relationship.     

Glutathione S-transferases GSTM1 and GSTT1 polymorphisms and asbestosis

OBJECTIVE: In a nested case-control study, the authors investigated whether the deletion polymorphism of glutathione S-transferases GSTM1 and GSTT1 represents a risk factor for the development of asbestosis. METHODS: In total, 262 cases with asbestosis and 265 controls, selected from a cohort of 2080 workers occupationally exposed to asbestos, were genotyped for GSTM1 and GSTT1-null alleles. Cumulative exposure for each subject was available. RESULTS: Asbestosis was associated with cumulative exposure (odds ratio [OR]=3.21, confidence interval [CI] 2.43-4.23) and GSTT1-null genotype (OR=0.61, CI 0.40-0.94), but not with GSTM1-null genotype (OR=1.01, CI 0.71-1.43). The risk of GSTM1-null and GSTT1-null genotype for asbestosis did not change after adjustment by cumulative exposure, smoking, gender, and age. CONCLUSIONS: An important finding of this study is that GSTT1 gene deletion might have a protective effect on the development of asbestosis.     

GSTM1和GSTT1基因多态性与女性肺癌易感性的关系

目的：探讨谷胱苷肽硫转移酶M1（glutathione S-transferaseM1,GSTM1)和T1（glutathione S-transferaseT1,GSTT1)基因多态性与女性肺癌遗传易感性的关系。方法：采用病例－对照研究方法和多重PCR技术检测女性肺癌病例组42人和健康对照组55人的GSTM1和GSTT1基因缺陷型的频率，并评价GSTM1和GSTT1基因型以及他们之间的交互作用与肺癌遗传易感性的关系。结果：在本次研究的人群中，病例组GSTM1和GSTT1基因缺陷型的频率分别为66．7％和45．2％，对照组为54．5％和38．2％，GSTM1基因缺陷型和GSTT1基因缺陷型的频率在病例组和对照组之间均无显性差异（P＞0．05）。在不吸烟的女性人群中，GSTM1基因缺陷型携带患肺癌的危险性是GSTM1基因功能型携带的2．557倍（P＝0．046）；GSTT1基因缺陷型则有女性肺癌的发生无显关联（P＝0．557）。此外，GSTT1基因型与GSTM1基因型之间亦无明显的交互作用（P＞0．05）。结论：GSTM1基因缺陷型可能是非吸烟女性患肺癌的重要危险因素。GSTT1基因缺失则可能与肺癌的发生无关，在女性肺癌的发生过程中GSTM1和GSTT1可能不存在交互作用。     

中国汉族人口三种谷胱甘肽S-转移酶基因多态性分析

目的：分析中国汉族人口谷胱甘肽S－转移酶（GSTs)基因多态性分布。方法：样本为450名中国汉族人口,采用多重等位基因特异聚合酶链反应（PCR）方法分析GSTM1和GSTT1基因多态性,采用PCR－限制性片段长度多态性方法分析GSTP1＋313核苷酸位点的基因多态性。结果：GSTM1缺失型和GSTT1缺失型基因型频率分别为57％和45％,同时具有GSTM1缺失型和GSTT1缺失型基因型的人个体频率为28．92％;而GSTP1＋313位点G等位基因频率为18．7％,并发现该人群中同时具有3种危险基因型（GSTM1缺失型、GSTT1缺失型和GSTP1＋313A／A）的个体频率为18．04％。GSTs基因型分布不受性别和年龄的影响。结论：中国汉族人口GSTM1、GSTT1和GSTP1基因呈多态性分布,其等位基因和基因型频率不同于其他种族。     

Genetic influences on the retention of inorganic mercury

Mercury is eliminated as glutathione (GSH) conjugates. GSH production is mediated by glutamyl-cysteine ligase (GCL), and conjugation by glutathione S-transferases (GST). This study tested if polymorphisms in GCL and GST genes modify mercury retention in humans exposed to elemental mercury vapor. Total mercury concentrations in whole blood, plasma and urine, and genotypes for GCLC, GCLM, GSTA1, GSTM1, GSTP1, and GSTT1 were determined in 309 gold miners, gold buyers and controls. The presence of the GCLM-588T allele was associated with increased blood, plasma and urine mercury levels. These results indicate that genotypes with decreased GSH availability for mercury conjugation affect the metabolism of inorganic mercury.     

谷胱甘肽转硫酶M1和T1基因型与新疆哈萨克族食管癌的关系

目的 为探讨与致癌物代谢有关的谷胱甘肽转硫酶(GST)Tl和Ml基因多型性与哈萨克族食管癌易感性的关系。方法 采用聚合酶链(PCR)技术，分析新疆食管癌高发民族中GSTMl和GSTTl基因型分布的差异。结果 GSTMl基因在食管癌、癌旁正常粘膜对照组中缺失率分别为41．46％(17／41)、34．15％(14／41)；GSTTl基因缺失率的分别为48．78％(20／41)、51．22％(21／41)，差别均无显性。同时，在食管癌组织的高分化组、中低分化组中GSTTl和GSTMl基因缺失率分别为61．54％(8／13)、42．86％(12／28)、l5．38％(2／l3)、53．57％(14／28)，其中GSTMl基因缺失率在高、中低分化组中差别有统计学意义。结论 提示GSTMl基因多型性与哈萨克族食管癌组织病理分级相关。     

Association of Xenobiotic Metabolizing Enzymes Genetic Polymorphisms With Esophageal Cancer in Kashmir Valley and Influence of Environmental Factors

The Kashmir Valley has an elevated incidence rate of esophageal cancer (EC). Several environmental and genetic factors have been suspected for development of EC. A case-control study was performed in 135 EC patients and 195 healthy controls to analyze association of polymorphisms in glutathione S-transferase (GST) mu (GSTM1), GST theta (GSTT1), GST pi (GSTP1), GSTM3, Cytochrome P450 (CYP)1A1, and CYP2E1 genes with susceptibility to EC as well as their interaction with environmental factors such as smoking and high consumption of salted tea in Kashmir valley. All subjects were genotyped through polymerase chain reaction restriction fragment length polymorphism. Data was statistically analyzed using the chi-square test and logistic regression model. Results showed that GSTP1313 val/val and CYP2E1c1c2 genotypes imparted risk for esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma [EADC; odds ratio (OR) = 3.24, 95% confidence interval (CI) = 1.30–8.05; OR = 4.20, 95% CI = 1.65–10.70], respectively. GSTM3AB genotype/B allele was found to be associated with low risk for EC. Tobacco smoking through hukka (water pipe) and consumption of salted tea itself were high risk factors for developing EC (OR = 21.44, 95% CI = 11.63–39.54; OR = 14.86, 95% CI = 8.41–26.24), and the risks were modulated through the interaction of GSTM3AB, GSTP1val/val genotypes. In conclusion, GSTP1val/val and CYP2E1c1c2 genotypes/c2 allele increased the risk of ESCC and EADC, respectively, in the Kashmiri population; whereas GSTM3AB genotype imparted lower risk for both ESCC and EADC.     

GSTM1, GSTT1, GSTP1, and GSTA1 polymorphisms and urinary isothiocyanate metabolites following broccoli consumption in humans

Isothiocyanates (ITC) are potentially anticarcinogenic phytochemicals formed from the metabolism of glucosinolates and are found in cruciferous vegetables as well as a select number of other foods. ITC are both substrates for and inducers of glutathione S-transferase (GST) phase II metabolizing enzymes involved in carcinogen detoxification as well as effectors of phase I pathways. Previous studies report mixed results on the interaction between cruciferous vegetable intake, GST polymorphisms, and risk of cancer. We conducted a study of 114 healthy human subjects between 18 and 50 y of age to examine the biologic mechanism underlying the associations, specifically, to assess whether GST genotype is associated with urinary ITC metabolites following a known dose of broccoli. After 48 h of abstaining from all sources of glucosinolates, participants provided a blood sample, consumed 1 meal containing 2.5 g broccoli/kg body weight, and collected urine for 24 h. ITC metabolites were measured in the urine using a HPLC cyclocondensation assay. DNA was extracted from blood samples, and GSTM1 deletion, GSTT1 deletion, GSTP1 Ile105Val, and GSTA1*A/*B were genotyped by matrix-assisted laser desorption/ionization time-of-flight. A chi-square test was used to compare high and low ITC excretion levels across genotypes. ITC levels were regressed on genotype, adjusting for gender. There were no substantial differences in ITC levels among genotypes, either individually or in combination. Contrary to our hypothesis, a higher proportion of GSTM1 null individuals had high ITC excretion (62%) compared with the proportion of GSTM1 present with high ITC excretion (39%) (P = 0.03). These results are in agreement with another feeding study, and lend support to the idea of alternative routes of ITC metabolism.     

Effects of APOE rs429358, rs7412 and GSTM1/GSTT1 Polymorphism on Plasma and Erythrocyte Antioxidant Parameters and Cognition in Old Chinese Adults

Apolipoprotein E (APOE) and oxidative damage were correlated with the risk of Alzheimer’s disease (AD). Glutathione S-transferase (GST) polymorphism was proved to be associated with body antioxidant capacity and involved in the oxidative damage related chronic diseases. To explore the combined effects of APOE rs429358, rs7412 and GSTM1/T1 polymorphism on antioxidant parameters and cognition in old Chinese adults, a community-based cross-sectional study was carried out in 477 Chinese adults aged from 55 to 75. Information on demography and lifestyle of the participants was collected with a questionnaire. Cognitive function was measured by using a Montreal Cognitive Assessment (MoCA) test. Fasting venous blood samples were collected for APOE rs429358, rs7412 and GSTM1/T1 genotyping, and parameter measurement. No association of APOE rs7412, rs429358 and GSTM1/T1 polymorphisms with cognition was detected in the old Chinese adults. APOE rs429358, rs7412 polymorphism was mainly associated with plasma α-tocopherol, low density lipoprotein cholesterol (LDL-C) and plasma total antioxidant capacity (T-AOC) levels (p < 0.05). Interaction of APOE rs429358 and GSTT1 genotype on the plasma triglyceride (TG) level and erythrocyte catalase (CAT) and GST enzyme activities were detected (p < 0.05). The subjects with APOE rs429358 T/C + C/C and GSTT1− genotype were found to have the highest plasma TG level, erythrocyte CAT enzyme activity, and the lowest GST enzyme activity compared to subjects with other genotypes (p < 0.05). Lowest erythrocyte CAT enzyme activity and highest glutathione peroxidase (GSH-Px) enzyme activity were detected in the subjects with APOE rs7412 T/C + T/T and GSTM1+ genotype as compared with subjects with other genotypes. The levels of plasma and erythrocyte antioxidant parameters were APOE genotype associated. GSTM1 or GSTT1 genotype modified the influence of APOE rs7412, rs429358 polymorphism on antioxidant parameters.     

Polymorphisms in Glutathione-Related Genes Affect Methylmercury Retention

Methylmercury is eliminated from the human body as glutathione (GSH) conjugates. GSH production is mediated by glutamyl-cysteine ligase (GCL) and conjugation by glutathione S-transferases (GST). In this study, the authors tested whether polymorphisms in GCL and GST genes modify methylmercury retention. Erythrocyte mercury concentration (EryHg), plasma polyunsaturated fatty acids (PPUFA), and genotype for GCLC, GCLM, GSTA1, GSTM1, GSTP1 and GSTT1 were determined in 365 individuals. A general linear model was developed for analyzing whether genotype modified the regression of EryHg on PPUFA. The presence of one variant allele for either GCLC-129 or GSTP1-114 was associated with higher EryHg and steeper regression slope. No similar trends were shown for GCLM, GSTA1, GSTM1 or GSTT1. These findings indicate that GCLC polymorphisms that affect GSH production also affect methylmercury retention, and that GSTP1 may play a role in conjugating methylmercury with GSH.     

GSTM1, GSTT1, and GSTP1 polymorphisms, breast cancer risk factors and mammographic density in women submitted to breast cancer screening

Genetic polymorphisms in genes related to the metabolism of xenobiotics, such as genes of the glutathione S-transferases (GSTM1, GSTT1, and GSTP1) superfamily have been associated with an increased risk for breast cancer (BC). Considering the high incidence of BC in the city of Porto Alegre in southern Brazil, the purpose of this study was to characterize genotypic and allelic frequencies of polymorphisms in GSTM1, GSTT1, and GSTP1, and correlate these molecular findings with established risk factors for breast cancer including mammographic density, in a sample of 750 asymptomatic women undergoing mammographic screening. Molecular tests were performed using the multiplex polymerase chain reaction (PCR) for GSTM1 and GSTT1, and quantitative PCR for GSTP1 polymorphisms. Overall, the frequencies of GSTM1 and GSTT1 null genotypes were 45% and 21%, respectively. For GSTP1 polymorphism, genotypic frequencies were 44% for the Ile/Ile genotype, 44% for the Ile/Val genotype, and 12% for Val/Val genotype, with an allelic frequency of 66% for the wild type allele in this population, similar to results of previous international publications. There was a statistically significant association between the combined GSTM1 and GSTT1 null genotypes (M-/T-) and mammographic density in post menopausal women (p = 0.031). When the GSTT1 null (T-) genotype was analyzed isolated, the association with mammographic density in post menopausal women and in the overall sample was also statistically significant (p = 0.023 and p = 0.027, respectively). These findings suggest an association of GSTM1 and GSTT1 null genotypes with mammographic density.     

Glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) null polymorphisms, smoking, and their interaction in oral cancer: a HuGE review and meta-analysis

The association between glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) null polymorphisms and oral cancer is not consistent across studies, and data on their interaction with smoking in oral cancer are lacking. The authors systematically searched PubMed and SciVerse Scopus for case-control studies examining the association between null genotypes of the GSTM1 and GSTT1 genes and oral cancer. Twenty-eight case-control studies published in English were identified. Summary odds ratios were derived via random-effects models. The summary odds ratio for the GSTM1 null genotype was 1.43 in Asians (95% confidence interval (CI): 1.14, 1.78; P < 0.01, I (2) = 73%) and 0.98 in Caucasians (95% CI: 0.76, 1.28; P = 0.91, I (2) = 0%). Case-only analysis of 6 studies (552 cases) showed an inverse multiplicative interaction between GSTM1 null polymorphisms and smoking (ever/high levels of smoking vs. never/low levels) (odds ratio (OR) = 0.51, 95% CI: 0.32, 0.82; P = 0.01, I (2) = 34%). The GSTT1 null genotype was not significantly associated with oral cancer in Asians (OR = 1.07, 95% CI: 0.82, 1.38; P = 0.63, I (2) = 65%) or Caucasians (OR = 1.04, 95% CI: 0.41, 2.65; P = 0.93, I (2) = 55%). In conclusion, the GSTM1 null genotype may be associated with a higher risk of oral cancer in Asians but not in Caucasians, and this effect may be modified by smoking status. The GSTT1 null genotype may not be associated with oral cancer.     

谷胱甘肽转硫酶M1和T1基因型与食管癌危险性:病例-对照研究

为探讨参与致癌物代谢的谷胱甘肽转硫酶（ＧＳＴ）Ｍ１和Ｔ１基因多型性与食管癌危险性的关系，以病例－对照分子流行病学方法，分析食管癌高发区河南林县的食管癌、食管上皮重度增生病例和性别、年龄配对的正常对照者（各４５例）的ＧＳＴＭ１和ＧＳＴＴ１基因型分布的差异。基因组ＤＮＡ来自研究对象的食管外科手术标本或细胞学检查获得的食管上皮细胞，以多重聚合酶链反应方法进行基因分型。结果：食管癌、食管上皮重度增生病例和