Genetic polymorphism of glutathione S-transferase M1 and T1 in Delhi population of Northern India

Evaluation of genetic instability, oxidative stress, and metabolism-related gene polymorphisms in workers exposed to waste anesthetic gases

Professionals who work in operating rooms (ORs) may be exposed daily to waste anesthetic gases (WAGs) due to the use of inhalational anesthetics. Considering the controversial findings related to genetic damage and redox status in addition to a lack of knowledge about the effect of polymorphisms in genes related to phase I and II detoxification upon occupational exposure to WAGs, this cross-sectional study is the first to jointly evaluate biomarkers of genetic instability, oxidative stress, and susceptibility genes in professionals occupationally exposed to high trace amounts of halogenated (≥ 7 ppm) and nitrous oxide (165 ppm) anesthetics in ORs and in individuals not exposed to WAGs (control group). Elevated rates of buccal micronucleus (MN) and nuclear bud (NBUD) were observed in the exposure group and in professionals exposed aged more than 30 years. Exposed males showed a higher antioxidant capacity, as determined by the ferric reducing antioxidant power (FRAP), than exposed females; exposed females had higher frequencies of MN and NBUD than nonexposed females. Genetic instability (MN) was observed in professionals with greater weekly WAG exposure, and those exposed for longer durations (years) exhibited oxidative stress (increased lipid peroxidation and decreased FRAP). Polymorphisms in metabolic genes (cytochrome P450 2E1 (CYP2E1) and glutathione S-transferases (GSTs)) did not exert an effect, except for the effects of the GSTP1 (rs1695) AG/GG polymorphism on FRAP (both groups) and GSTP1 AG/GG and GSTT1 null polymorphisms, which were associated with greater FRAP values in exposed males. Minimizing WAG exposure is necessary to reduce impacts on healthcare workers.

Elevated exposure to polycyclic aromatic hydrocarbons (PAHs) may trigger cancers in Pakistan: an environmental, occupational, and genetic perspective

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds which are emitted through incomplete combustion of organic materials, fossil fuels, consumption of processed meat, smoked food, and from various industrial activities. High molecular mass and mobility make PAHs widespread and lethal for human health. A cellular system in human detoxifies these toxicants through specialized enzymatic machinery called xenobiotic-metabolizing (CYP450) and phase-II (GSTs) enzymes (XMEs). These metabolizing enzymes include cytochromes P450 family (CYP1, CYP2), glutathione s-transferases, and ALDHs. Gene polymorphisms in XMEs encoding genes can compromise their metabolizing capacity to detoxify ingested carcinogens (PAHs etc.) that may lead to prolong and elevated exposure to ingested toxicants and may consequently lead to cancer. Moreover, PAHs can induce cancer through reprograming XMEs' gene functions by altering their epigenetic markers. This review article discusses possible interplay between individual's gene polymorphism in XMEs' genes, their altered epigenetic markers, and exposure to PAHs in cancer susceptibility in Pakistan.

Interaction of glutathione-s-transferase genotypes with environmental risk factors in determining susceptibility to head and neck cancer and treatment response and survival outcome

The present case-control study aimed to investigate the role of interaction of glutathione-s-transferase (GST) genotypes with environmental risk factors in determining susceptibility to head and neck squamous cell carcinoma (HNSCC) involving 1,250 cases and equal number of healthy controls. An increase in the risk of HNSCC and its subsites (larynx, pharynx, and oral cavity) was observed among the cases with null genotypes of GSTM1 (odds ratio [OR] = 1.87) or GSTT1 (OR = 1.39) while reduced risk (OR = 0.81) was observed the cases with variant genotype of GSTP1. Tobacco use in the form of smoking or chewing interacted multiplicatively with GSTM1 or GSTT1 to increase the risk several folds (3-10 folds) in HNSCC and its subsites. Alcohol use also increased the risk (2-3 folds) to HNSCC and its subsites in cases with null or variant genotypes of GSTs, though this risk was of lesser magnitude when compared to the tobacco users. A synergistic effect of both, tobacco smoking and alcohol drinking, led to several folds (25-folds) increased risk to HNSCC among the cases with null genotype of GSTM1 and GSTT1 when compared to nonsmokers and nondrinkers with wild genotype of GSTM1 and GSTT1 in controls. Furthermore, cases with variant genotypes of GSTP1 (Val/Val) showed superior treatment response with improved survival rate and lower risk of death when compared to the patients with wild type genotype (Ile/Ile). The data suggest that though polymorphism in GSTs may be a modest risk factor for determining HNSCC risk, gene-environment interactions significantly modify the susceptibility to HNSCC by several folds.

Polymorphism of Glutathione S-transferase Genes and the Risk of Toxic Liver Damage in Petrochemical Workers

BACKGROUND

Exposure to numerous chemicals, including industrial ones, may result in liver damage. The body susceptibility to the environmental hazards largely depends on the activity of the enzymes in the xenobiotic detoxification system. Function abnormalities of such enzymes due to genetic variations would increase the risk of developing various diseases.

OBJECTIVE

To elucidate the relationship between polymorphism in glutathione S-transferase genes (GSTM1, GSTT1 and GSTP1) and the risk of toxic liver damage in a group of petrochemical workers.

METHODS

This study was conducted on 72 workers with toxic liver injury, 156 healthy workers, and 322 healthy individuals without history of occupational exposure to chemicals. Genotyping of the GSTP1 rs1695 gene polymorphism was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Polymerase chain reaction (PCR) was used to perform genotyping of the GSTM1 and GSTT1 genes polymorphism.

RESULTS

There was a significant difference in genotype frequencies of the GSTP1 rs1695 gene polymorphism among the groups studied. The distribution of Val/Val genotype of the GSTP1 rs1695 gene polymorphism had a higher incidence in healthy workers compared with patients with toxic liver damage (p=0.036). No significant association was found between the GSTM1 and GSTT1 polymorphisms and toxic liver damage.

CONCLUSION

The GSTP1 rs1695 gene polymorphism can play a protective role in the development of toxic liver damage in petrochemical workers.

Tracing biomarker of PAH-exposure and susceptibility factor (GSTM-polymorphism) among cancer patients in Pakistan

We studied cancer patients for possible PAH exposure, using urinary concentration of 1-hydroxypyrene (1-OHP) as a biomarker of internal dose of polycyclic aromatic hydrocarbons (PAHs). The subjects included in this study belonged to various socio-demographic backgrounds, and were diagnosed with cancer (i.e. lung, head and neck or digestive tract cancer). In general, we observed high concentration of urinary 1-OHP among digestive tract cancer patients, compared with the controls (CN) (mean 1.06, median 1.03 and mean 0.62, median 0.63 μmol/mol-Cr in digestive tract cancer patients and controls respectively). The concentrations of urinary 1-OHP were higher than the background level of PAHs; therefore, these groups could have been exposed to PAHs. Highest urinary 1-OHP concentration was observed in digestive tract cancer patients (median 1.25 μmol/mol-Cr) with GSTM-1 genotype. The results of PCA were consistent with qualitative and quantitative data analysis. The contribution of urinary 1-OHP eigenvector revealed a relatively high PAH-exposure among cancer patients compared with CN, while diet and age were influential parameters among cancer patients, which could have a strong link in cancer etiology in the selected exposure groups.

Analyses of Genetic Variations of Glutathione S-Transferase Mu1 and Theta1 Genes in Bangladeshi Tannery Workers and Healthy Controls

Glutathione S-transferases (GSTs) belong to a group of multigene detoxification enzymes, which defend cells against oxidative stress. Tannery workers are at risk of oxidative damage that is usually detoxified by GSTs. This study investigated the genotypic frequencies of GST Mu1 (GSTM1) and GST Theta1 (GSTT1) in Bangladeshi tannery workers and healthy controls followed by their status of oxidative stress and total GST activity. Of the 188 individuals, 50.0% had both GSTM1 and GSTT1 (+/+), 12.2% had GSTM1 (+/-), 31.4% had GSTT1 (-/+) alleles, and 6.4% had null genotypes (-/-) with respect to both GSTM1 and GSTT1 alleles. Among 109 healthy controls, 54.1% were double positive, 9.2% had GSTM1 allele, 32.1% had GSTT1 allele, and 4.6% had null genotypes. Out of 79 tannery workers, 44.3% were +/+, 16.8% were +/-, 30.5% were -/+, and 8.4% were -/-. Though the polymorphic genotypes or allelic variants of GSTM1 and GSTT1 were distributed among the study subjects with different frequencies, the differences between the study groups were not statistically significant. GST activity did not vary significantly between the two groups and also among different genotypes while level of lipid peroxidation was significantly higher in tannery workers compared to controls irrespective of their GST genotypes.

Technical reproducibility of single-nucleotide and size-based DNA biomarker assessment using DNA extracted from formalin-fixed, paraffin-embedded tissues

DNA extracted from formalin-fixed, paraffin-embedded (FFPE) tissues has been used in the past to analyze genetic polymorphisms. We evaluated the technical reproducibility of different types of assays for gene polymorphisms using DNA extracted from FFPE material. By using the MassARRAY iPLEX system, we investigated polymorphisms in DPYD (rs1801159 and rs3918290), UMPS (rs1801019), ERCC1 (rs11615), ERCC1 (rs3212986), and ERCC2 (rs13181) in 56 FFPE DNA samples. By using PCR, followed by size-based gel electrophoresis, we also examined TYMS 5' untranslated region 2R/3R repeats and GSTT1 deletions in 50 FFPE DNA samples and 34 DNAs extracted from fresh-frozen tissues and cell lines. Each polymorphism was analyzed by two independent runs. We found that iPLEX biomarker assays measuring single-nucleotide polymorphisms provided consistent concordant results. However, by using FFPE DNA, size-based PCR biomarkers (GSTT1 and TYMS 5' untranslated region) were discrepant in 32.7% (16/49, with exact 95% CI, 19.9%-47.5%; exact binomial confidence limit test) and 4.2% (2/48, with exact 95% CI, 0.5%-14.3%) of cases, respectively, whereas no discrepancies were observed using intact genomic DNA. Our findings suggest that DNA from FFPE material can be used to reliably test single-nucleotide polymorphisms. However, results based on size-based PCR biomarkers, and particularly GSTT1 deletions, using FFPE DNA need to be interpreted with caution. Independent repeated assays should be performed on all cases to assess potential discrepancies.

Distributions of the GSTM1 and GSTT1 null genotypes worldwide are characterized by latitudinal clines

BACKGROUND

Deletion types of genetic variants of glutathione S-transferase (GST) M1 and T1, the GSTM1 null and GSTT1 null which are risk factors for certain cancers, have been ubiquitously found in human populations but their worldwide distribution pattern is unclear.

MATERIALS AND METHODS

To perform a meta-analysis, a systematic search for the literature on GSTM1 and GSTT1 null genotypes was done to identify 63 reports for 81 human populations. Relationships between the GSTM1 and GSTT1 null genotype frequencies and the absolute latitude of 81 populations were tested by Spearman's rank correlation coefficient.

RESULTS

A significant positive correlation was detected between the GSTM1 null genotype frequency and the absolute latitude (r=0.28, p-value <0.05), whereas the GSTT1 null genotype frequency and absolute latitude showed a significant negative correlation (r= -0.41 p-value <0.01). There was no correlation between the frequencies of GSTM1 and GSTT1 null genotype in each population (r= -0.029, p-value=0.80).

CONCLUSIONS

Latitudinal clines of the distribution of the GSTM1 and GSTT1 null genotypes may be attributed to the result of gene-environmental adaptation. No functional compensation between GSTM1 and GSTT1 was suggested by the lack of correlation between the null frequencies for GSTM1 and GSTT1.

Genetic polymorphisms of GSTM1 and GSTT1 genes in Delhi and comparison with other Indian and global populations

The glutathione S-transferases (GSTs) are involved in the metabolism of many xenobiotics, including an array of environmental carcinogens, pollutants, and drugs. Genetic polymorphisms in these genes may lead to inter- individual variation in susceptibility to various diseases. In the present study, GSTM1 and GSTT1 polymorphisms were analysed using a multiplex polymerase chain reaction in 500 normal individuals from Delhi. The frequency of individuals with GSTM1 and GSTT1 null genotypes were 168 (33.6%) and 62 (12.4%) respectively, and 54 (10.8%) were having homozygous null genotype for both the genes GSTM1 and GSTT1 simultaneously. The studied population was compared with reported frequencies from other neighbouring state populations, as well as with those from other ethnic groups; Europeans, Blacks, and Asians. The prevalence of homozygous null GSTM1 genotype is significantly higher in Caucasians and Asians as compared to Indian population. The frequency of GSTT1 homozygous null genotypes is also significantly higher in blacks and Asians. We believe that due to large number of individuals in this study, our results are reliable estimates of the frequencies of the GSTM1, GSTT1 in Delhi. It would provide a basic database for future clinical and genetic studies pertaining to susceptibility and inconsistency in the response and/or toxicity to drugs known to be the substrates for GSTs.

A preliminary study on the influence of glutathione S transferase T1 (GSTT1) as a risk factor for late onset Alzheimer's disease in North Indian population

INTRODUCTION

Oxidative stress plays key role in pathogenesis of Alzheimer's disease. Glutathione S-transferases (GSTs), a family of phase-II isoenzymes, play a critical role in providing protection against electrophiles and products of oxidative stress. Among different classes of GSTs, GSTM1 (Mu) and GSTT1 (theta) are found to be genetically deleted which results in decreased expression of the concerned enzyme. This study aims at preliminary analysis of the frequency of deletion of GSTM1 and GSTT1 and their association with late-onset Alzheimer's disease.

MATERIAL AND METHODS

In this study, association of the deletion type polymorphism of GST M1 and T1 as possible risk factors for dementia of Alzheimer's type was studied in 50 patients and 100 controls. Dementia was diagnosed by Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria, Mini Mental State Examination (MMSE) and Clinical Dementia Rating (CDR) scale. Genotyping was done by multiplex Polymerase Chain Reaction (PCR). Associations between null genotype of either GSTM1 and GSTT1 or both with Alzheimer's disease were analyzed by Chi-Square test.

RESULTS

Deletion of GSTT1 was found significantly associated with Alzheimer's disease (χ(2)=5.08, p=0.02*).

CONCLUSIONS

The odds of Alzheimer's disease in null GSTT1 is found to be increased by 2.47 times in comparison to positive GSTT1.

A case control study of gene environmental interaction in fetal growth restriction with special reference to organochlorine pesticides

OBJECTIVES

Organochlorine pesticides (OCPs) and oxidative stress are reported to be associated with adverse reproductive outcomes. Glutathione S-transferase (GST) is a polymorphic supergene family involved in the detoxification of numerous toxins including OCPs. OCPs are endocrine disrupter and prenatal exposure to them may be associated with fetal growth restriction (FGR). The objectives of the present study were (i) to determine the frequencies of polymorphic alleles of GSTM1 and GSTT1 genes in women with idiopathic FGR, (ii) to analyze the maternal and cord blood levels of the OCPs, and (iii) to identify the gene environment interaction that increases the risk of FGR.

STUDY DESIGN

Maternal and cord blood samples of 50 FGR cases (birth weight <10 percentile for gestational age as per Lubchenco's growth chart) and equal number of normal pregnancies who were occupationally non exposed to OCPs and excluding all the known high risk factors such as anemia, hypertension, antiphospholipid antibody syndrome, medical disease, dietary habit, living style, parity, and BMI. The collected samples at the time of delivery/after delivery were analyzed for OCPs levels by gas chromatography and polymorphic analysis for GSTM1/GSTT1 gene using multiplex PCR.

RESULTS

Significantly higher levels of α,β,γ-HCH and p,p'-DDT were found in maternal blood and significantly higher levels of β and γ-HCH and p,p'-DDT were found in cord blood of FGR cases as compared to controls. The genotypic distribution of GSTM1/GSTT1 was almost similar in both the groups, but the frequency of GSTM1-/GSTT1- (null) genotype was significantly higher in FGR cases as compared to controls (p<0.05, OR=6.42). When interaction between GSTM1/GSTT1 genes polymorphism-OCPs levels and birth weight (gene-environment interaction) was ascertained, a significant association was seen between β-HCH and GSTM1- genotype with reduction in birth weight of 213g.

CONCLUSION

Higher levels of OCPs in pregnant women may be considered as an important aetiological factor in 'idiopathic' FGR. GST polymorphism can influence the relationship between prenatal exposure to pesticides and FGR. The present study provides evidence that polymorphism in xenobiotic metabolising genes may modify the effect of environmental health hazards and increase the risk of FGR.

Influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to organophosphate pesticides

Previous studies have revealed that organophosphate pesticides (OPs) are primarily metabolized by xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticides-exposed workers. Present study was designed to determine the influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to OPs. We examined 268 subjects including 134 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using alkaline comet assay and genotyping was done using individual polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Acetylcholinesterase and paraoxonase activity were found to be significantly lowered in workers as compared to control subjects which were analyzed as biomarkers of toxicity due to OPs exposure (p<0.001). Workers showed significantly higher DNA tail moment (TM) compared to control subjects (14.32±2.17 vs. 6.24±1.37 tail % DNA, p<0.001). GSTM1 null genotype was found to influence DNA TM in workers (p<0.05). DNA TM was also found to be increased with concomitant presence of NAT2 slow acetylation and CYP2C9*3/*3 or GSTM1 null genotypes (p<0.05). DNA TM was found increased in NAT2 slow acetylators with mild and heavy smoking habits in control subjects and workers, respectively (p<0.05). The results of this study suggest that GSTM1 null genotypes, and an association of NAT2 slow acetylation genotypes with CYP2C9*3/*3 or GSTM1 null genotypes may modulate DNA damage in workers occupationally exposed to OPs.

Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides

GSTM1, T1 and P1 are important enzymes of glutathione S-transferases (GSTs), involved in the metabolism of many endogenous and exogenous compounds. Individual genetic variation in these metabolizing enzymes may influence the metabolism of their substrates. The present study was designed to determine the genotoxic effects using DNA damage and its association with GSTM1, GSTT1, and GSTP1 (Ile105Val) genetic polymorphisms in workers occupationally exposed to organophosphate pesticides (OPs). We examined 230 subjects including 115 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using individual PCR or PCR-RFLP. Significantly higher DNA tail moment (TM) was observed in workers as compared to control subjects (14.41 ± 2.25 vs. 6.36 ± 1.41 tail % DNA, p<0.001). The results revealed significantly higher DNA TM in workers with GSTM1 null genotype than those with GSTM1 positive (15.18 vs. 14.15 tail % DNA, p=0.03). A significantly higher DNA TM was also observed in workers with homozygous Ile-Ile GSTP1 genotype than heterozygous (Ile-Val) and mutant (Val-Val) GSTP1 genotype (p=0.02). In conclusion, the results show that null deletion of GSTM1 and homozygote wild GSTP1 genotype could be related to inter-individual differences in DNA damage arises from the gene-environment interactions in workers occupationally exposed to OPs.

Association of glutathione S-transferase M1 and T1 gene polymorphism with oxidative stress in diabetic and nondiabetic chronic kidney disease

BACKGROUND AND OBJECTIVE

Glutathione S-transferases (GSTs) belong to a family of ubiquitous and multifunctional enzymes that work as one of the endogenous antioxidants in our body. This study was designed to look into the association of GST polymorphism with oxidative stress in both diabetic and nondiabetic chronic kidney disease (CKD).

DESIGN AND METHODS

Three groups of patients (50 in each): diabetics without CKD (DM), diabetic CKD (DM-CKD), and nondiabetic CKD (NDM-CKD) and 50 age- and sex-matched healthy controls were recruited. Genotyping was done for GSTM1 and GSTT1 genes using a multiplex polymerase chain reaction. Serum GST and malondialdehyde (MDA) as a marker of oxidative stress were measured spectrophotometrically.

RESULTS

Based on genotyping, subjects were categorized as GSTM1+/GSTT1+, GSTM1-/GSTT1+, GSTM1+/GSTT1-, and GSTM1-/GSTT1-. Serum GST levels were lower among subjects with deletion in one/both GST genes, whereas MDA levels were found to be correspondingly raised. A negative correlation for MDA versus GST levels was observed among genotypes with one/both gene deletions. Presence of GSTM1+/GSTT1- and GSTM1-/GSTT1- was significantly higher among patients with CKD in both diabetics and nondiabetics.

INTERPRETATIONS AND CONCLUSIONS

GSTM1 and GSTT1 deletions singly or together were associated with lower GST levels and higher oxidative stress in both diabetic and nondiabetic CKD. Interestingly, GSTT1 deletion appears to be associated with both diabetic and nondiabetic CKD irrespective of the GSTM1 status.

Polymorphism in CYP1A1, GSTMI,GSTT1 genes and organochlorine pesticides in the etiology of hypospadias

Exposure to endocrine-disrupting chemicals (EDCs) and maternal endogenous estrogen may cause hypospadias, common congenital anomaly. Several organochlorine pesticides (OCPs) have been reported to possess an endocrine-disrupting potential. Cytochrome P4501A1 (CYP1A1) and glutathione S-transferases (GSTM1 and GSTT1) of xenobiotic metabolizing enzyme family are involved in the metabolism of various environmental toxicants and steroidal hormones. Hence, the present study was designed to evaluate the role of CYP1A1, GSTM1, GSTT1 genes polymorphism, OCPs levels and risk of hypospadias. A total of 80 hypospadiac and 120 age-matched control boys were included. OCP levels in blood were determined using Gas Chromatograph equipped with electron capture detector (GC-ECD) and polymorphism in CYP1A1, GSTM1 and GSTT1 genes was evaluated by RFLP and multiplex PCR method. We observed significant high levels of β-hexachlorohexane (HCH), γ-HCH, and p, p′-dichlorodiphenyl-dichloroethylene ( p,p’-DDE) in the cases. CYP1A1 polymorphisms were not significantly different among cases and controls, whereas concomitant deletion of GSTM1 and GSTT1 genotypes was significantly higher in cases as compared to controls. However, after adjusting for low birth weight and maternal occupational exposure, the results did not remain significant but odds of risk was higher (OR = 1.72, p = 0.14) among cases. In conclusion, our study suggests irrespective of genetic predisposition, higher level of some OCPs may be associated with increased risk of hypospadias.

Frequency distribution of GSTM1 and GSTT1 null allele in Pakistani population and risk of disease incidence

Glutathione-S-transferases, GSTM1 and GSTT1 play a significant role in detoxification and bioactivation of a broad range of xenobiotic compounds known to be mutagenic and/or carcinogenic. Deletion polymorphisms of these glutathione transferases (GSTM1 and GSTT1) predispose individuals to environmental carcinogenic compounds. Although a number of studies have shown the relationship between GSTM1 and/or GSTT1 deletion polymorphism and different cancers, these findings cannot be extrapolated to other populations due to intra- and inter-ethnic variability. In order to assess the impact of differential ethnicity on the occurrence of different cancers in local population due to GSTM1, or GSTT1 deletion polymorphism, 111 healthy male and female individuals of different age groups from Southern Punjab, Pakistan were genotyped using a multiplex polymerase chain reaction. From the results it is obvious that null alleles of GSTM1 and GSTT1 genes were found in 45% and 23% individuals, respectively. In 5% of individuals' simultaneous deletion of both GSTM1 and GSTT1 genes were observed. Frequency of GSTM1 null allele is in concordance with those documented for Chinese, Caucasians, Mongolian, and Japanese populations. However, a significantly higher frequency for GSTT1 null was reported in Chinese and Japanese population as compared to Pakistani population. It is the first ever report on frequency of GSTM1 and GSTT1 null allele in Pakistani population which demonstrate the impact of ethnicity and provide basis for future epidemiological and clinical studies.

CYP1A1 and CYP3A4 polymorphic variations in Delhi population of Northern India

Cytochrome P450 (CYP) 1A1 and CYP3A4 are important phase I xenobiotic metabolizing enzymes involved in the metabolism of numbers of toxins, endogenous hormones and pharmaceutical drugs. Polymorphisms in these phase I genes can alter enzyme activity and are known to be associated with cancer susceptibility related to environmental toxins and hormone exposure. Their genotypes may also display ethnicity dependent population frequencies. The present study was aimed to determine the frequencies of commonly known functional polymorphisms of CYP1A1 and CYP3A4 in North Indian population. Allelic frequency of CYP1A1 polymorphisms, m1, m2 and m4 were observed to be 40.3, 31.2 and 0% respectively. Frequency of CYP3A4*1B polymorphism was 0%. We observed inter as well as intra ethnic variation in the distribution of frequency of these polymorphisms. Analysis of polymorphisms in these genes might help in predicting the risk of cancer. Our results emphasize the need for more such studies in "high risk populations".

Frequency of common CYP1B1 polymorphic variations in Delhi population of Northern India

Cytochrome P4501B1 (CYP1B1) is an extrahepatic enzyme, important in the activation of procarcinogens. It is expressed in steroidegenic tissues and is active in the metabolism of estradiol. CYP1B1 polymorphisms have been shown to be associated with cancer susceptibility related to environmental toxins and hormone exposure. CYP1B1 is also involved in the metabolism of some clinically relevant anticancer drugs. Polymorphisms in the gene have also been associated in primary open-angle glaucoma (POAG). Their genotypes may also display ethnicity dependent population frequencies. Present study was aimed to determine the frequency of five known CYP1B1 polymorphisms in Delhi population. Frequency of CYP1B1 polymorphisms, CYP1B1*2, CYP1B1*3, CYP1B1*4 and CYP1B1*7 were found to be 39, 48.8, 47.3 and 17.07% respectively in normal, healthy individuals. Arg48Gly and Ala119Ser were found to be completely linked with each other. Analysis of CYP1B1 polymorphisms might help in predicting the risk of cancer as well as susceptibility to POAG. Our results emphasize the need for more such studies in "high risk populations".