August 2010
Volume 51, Issue 8
Free
Clinical and Epidemiologic Research  |   August 2010
The Association between Copy Number Variations in Glutathione S-transferase M1 and T1 and Age-Related Cataract in a Han Chinese Population
Author Affiliations & Notes
  • Jing Zhou
    From the Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong, China.
  • Jianyan Hu
    From the Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong, China.
  • Huaijin Guan
    From the Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong, China.
  • Corresponding author: Huaijin Guan, Department of Ophthalmology, Affiliated Hospital of Nantong University, China, 20 Xisi Road, Nantong, Jiangsu, China; gtnantongeye@gmail.com
Investigative Ophthalmology & Visual Science August 2010, Vol.51, 3924-3928. doi:10.1167/iovs.10-5240
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Jing Zhou, Jianyan Hu, Huaijin Guan; The Association between Copy Number Variations in Glutathione S-transferase M1 and T1 and Age-Related Cataract in a Han Chinese Population. Invest. Ophthalmol. Vis. Sci. 2010;51(8):3924-3928. doi: 10.1167/iovs.10-5240.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose.: To determine the contribution of copy number variation (CNV) in glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) to the susceptibility to age-related cataract (ARC) and its subtypes in a Han Chinese population.

Methods.: ARC cases (n = 279) and controls (n = 145) were included from a Han Chinese population–based prospective study. Quantitative RT-PCR and the ΔCt method were used to determine the presence of no, one, or multiple alleles of GSTM1 and GSTT1. The RNaseP gene was used as the internal control.

Results.: The GSTT1 null genotype was associated with ARC with an odds ratio (OR) of 1.56 (P < 0.05). Deletion of at least one GSTT1 allele also influenced the onset of ARC (OR = 2.16, P < 0.01). Consistent associations were observed between GSTT1 CNV and cortical cataract. The deletion of at least one GSTT1 allele was associated with an OR of 4.81 for developing cortical ARC (P < 0.001), although individuals who had more than two copies of GSTT1 had a reduced risk of cortical ARC (OR = 0.19, P < 0.05). The frequency of the GSTT1 null genotype in the Han Chinese population differed dramatically from that in Caucasians. No association was detected between GSTM1 CNV and ARC.

Conclusions.: An association was observed between GSTT1 CNV and ARC in a Han Chinese population. The GSTT1 CNV is most closely associated with cortical cataract risk. The loss of at least one GSTT1 allele increases the risk of cortical cataract, whereas gain in GSTT1 copy number reduces the risk.

Age-related cataract (ARC) is one of the leading causes of visual impairment and blindness among the elderly worldwide. 1 The global burden of blindness due to ARC is increasing as a result of a growing elderly population. 2 Clinically, ARC can be classified as nuclear, cortical, or posterior subcapsular cataract according to the degenerative region of lens. 
ARC is a complex disease with a broad spectrum of risk factors including age, sex, smoking, exposure to sunlight, estrogen sufficiency or deficiency, cardiovascular factors, and genetic background. 3 Various studies have indicated a significant genetic component to ARC risk. 4,5 A study on the familial aggregation of ARC reported that the probability of the development of nuclear cataract was significantly increased (OR = 2.07) among individuals with a sibling with nuclear cataract. 6 A family-based linkage study reported multiple ARC loci at 1q31, 2p24, 2q11, 4q28, 15q13, and 6p12-q12. 7 The potential role of gene structure variation in ARC development has been considered. For example, several studies have demonstrated the association between ARC and gene polymorphisms of αA-crystallin and EPHA2. 8,9  
Involvement of oxidative stress appears to be one of the critical events in the pathogenesis of ARC. Oxidative damage can result in several molecular changes, such as degradation, cross-linking, and aggregation of lens proteins that contribute to the development of cataracts. 5,811 Crystallins and other proteins in lens fiber cells do not turn over and must serve the lens for a lifetime. Thus, the lens must have efficient reducing and detoxification systems. Enzymes such as catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferase (GST) are thought to be essential in protecting the eye from oxidative damage. 8,9,12,13  
GSTs are a superfamily of phase II drug-metabolizing enzymes that catalyze the conjugation of reduced glutathione (GSH) with a variety of electrophilic compounds, thereby protecting the cell against xenobiotics and oxidative stress. 8,9,14,15 The members of the GST family include various isoforms, including α (GSTA), μ (GSTM), π (GSTP), κ (GSTK), θ (GSTT), and ζ (GSTZ), based on sequence identity. 16 Copy number variations (CNV) in GSTM1 and GSTT1 have been reported. 1719 The GSTM1*0/0 null allele may result from homologous unequal crossing over between two highly identical 4.2-kb repeated sequences flanking the GSTM1 gene, causing a 15-kb deletion including the entire GSTM1 gene. 18,19 A similar mechanism causes the generation of the GSTT1*0/0 null allele. 17  
Gene dosage effects between CNV and enzyme activity have been reported for both GSTM1 and GSTT1. 20,21 The null genotypes GSTM1*0/0 and GSTT1*0/0 are associated with complete loss of catalytic activity 17,22 and have been suggested to be associated with diseases that have oxidative stress in their pathogenesis. 2326 As mediators of protection against oxidative stress, GSTM1 and GSTT1 serve as excellent candidates for studies of ARC. Accordingly, several recent studies have investigated the influence of the presence or absence of GST gene deletions on human cataract with controversial results. 2730 By measuring protein level of GSTM1, GSTM1-present phenotype was reported to be associated with the development of cortical cataract in Estonians. 28 However, the GSTM1-null genotype or a combination of the GSTM1-null and GSTT1-present genotypes were found to be associated with increased risk of cataract development in a female Turkish population. 31 Results in another study in an Italian population showed no association between GSTM1 CNV and cataract. 28 A significant increase in GSTM1-null genotype frequency was observed in ARC cases in comparison with healthy controls in a Chinese population. 29 Conversely, in another study in a Chinese population, it was reported that the GSTM1-null genotype was not related to ARC. 30 These discrepancies may be partially explained by the fact that most studies were designed as hospital-based case–control studies that might have population stratification. Moreover, all studies were conducted by using traditional CNV assays that were unable to discriminate between carriers of one, two, or more than two gene copies. Another reason of the inconsistent conclusions may be the small sample sizes in some studies, which failed to afford sufficient power for statistically significant results. 
Quantitative real-time PCR assays have been recently devised to determine CNV. The method can discriminate between carriers of one or multiple GSTM1 and GSTT1 alleles with RNaseP as the endogenous calibrator beside the homogenous deletion of 2 alleles. 25,32,33 In this study, we recruited subjects with ARC and without ARC from a population-based prospective cohort in the Nantong area of Eastern China that was of sufficient size. We tested the hypothesis that CNV in GSTM1 and GSTT1 may contribute to ARC susceptibility in the Han Chinese population. 
Methods
Study Subjects
The research adhered to the tenets of the Declaration of Helsinki. All participants signed the respective informed consent forms. The study was approved by the Ethics Committee of Nantong University. 
The study was a part of the Nantong Eye Study, a population-based cohort study that focuses on common eye diseases and health-related parameters among 57,843 urban residents with 6,421 people older than 60 years according to the census data from 2000. The covered area of the Nantong Eye Study has a stable and ethnically homogenous population. The participants have been followed up for 10 years. The design and initial results of the study have been published. 34,35 The study participants were unrelated, self-identified Han Chinese (at least all four grandparents were ethnically Han Chinese). 
ARC was defined as the appearance of the clinical sign of cataract in one or both eyes in a person older than 50 years. 36 The clinical sign was characterized as opacity of the lens resulting in visual acuity of 20/40 or worse measured with Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. The patients with systemic diseases, a history of ocular trauma, secondary cataract due to glaucoma, age-related macular degeneration, uveitis, or diabetes and other known causes were excluded. We paid particular attention to the glycometabolic status of all participants and excluded those with abnormal blood glucose levels (fasting blood glucose >6.05 mmol/L) because a disorder of the galactose metabolic pathway was reported to be associated with cataract formation in an East Asian population. 37 The average fasting blood glucose levels are presented in Table 1. All patients with ARC and control subjects underwent a full ophthalmic examination, including visual acuity, lens examination in transient and side illumination with a slit lamp biomicroscope after mydriasis and ophthalmoscopic examination. Lens photographs from all participants were recorded by the same ophthalmologist at the same dark room. The opacity of the lens was classified using the lens opacities classification system II (LOCS II). 38 The grading was conducted by comparing slit lamp observations to standard LOCS II photos. The grading was later cross-checked by the group leader by comparing lens photographs with the same standard photos. We included only the cases with grades ≥NII of nuclear cataract, ≥CII of cortical cataract, or ≥PI of posterior subcapsular cataract. Individuals with a mixture of subtypes in one both eyes were excluded. The case group consisted of 279 ARC patients, among whom there were 131 with cortical cataract, 70 with nuclear cataract, and 78 with posterior subcapsular cataract. 
Table 1.
 
Demographics of Study Participants
Table 1.
 
Demographics of Study Participants
Group n Sex Age (y) Smoking n (%) Drinking n (%) Hypertension n (%) Blood Glucose (mmol/L)
Male n (%) Female n (%) Mean ± SD Range
Control 145 72 (49.7) 73 (50.3) 64.5 ± 4.2 59–82 32 (22.1) 40 (27.6) 38 (26.2) 4.9 ± 3.1
ARC 279 103 (36.9)* 176 (63.1)* 69.0 ± 8.4 50–92 89 (31.9)* 51 (18.3)* 109 (39.1)* 5.1 ± 4.0
The control group included 145 unrelated individuals with transparent lenses and visual acuity better than 20/25 in both eyes. The opacities in the lenses of both eyes corresponded to a grade of ≤N0 of the nuclear area, ≤Ctr of the cortical area, and ≤P0 of the posterior subcapsular area, according to LOCS II. The individuals with other major eye diseases such as dislocated lenses, glaucoma, age-related macular degeneration, diabetic retinopathy, uveitis, or systemic diseases such as diabetes, kidney diseases, and cancers were excluded from the control group. The cases and controls were matched as closely as possible for age and other factors. The demographic information for the study participants is summarized in Table 1
Blood glucose level, blood pressure, and liver and renal function were obtained and chest x-rays were performed in all subjects. Whole-blood samples were collected from every participant for genomic DNA extraction. 
Purification and Measurement of DNA
Genomic DNA was isolated from 200 μL of peripheral blood (QIAamp DNA Blood Mini Kit; Qiagen, Hilden, Germany) according to the manufacturer's protocol, eluted in a total volume of 200 μL, and stored at −20°C. 39 DNA concentrations were measured by UV absorbance (Gene Quant 100; Applied Biosystems [ABI], Foster City, CA). The samples from the cases and controls were collected during the same time period, and they were processed and stored using the same methods. 
Copy Number Determination by Relative Quantitative Real-Time PCR
All assay reagents were purchased from ABI. The primers and 6-FAM-labeled probes that were used to amplify GSTM1 and GSTT1 are listed in Table 2. The RNaseP control kit containing VIC-labeled probes and gene-specific primers was used as an endogenous control. The amplification of RNaseP and the GST genes in the same sample normalized the differences in DNA concentration between samples and ensured that no false-negative GST*0/0 genotypes due to PCR or pipetting failure or insufficient DNA concentrations in the original sample were generated. The initial step of the PCR reaction was set at 50°C for 2 minutes, and the denaturation step was performed at 95°C for 10 minutes. The amplification was performed for 40 cycles at 95°C for 15 seconds, and at 60°C for 1 minute. PCR was performed (model 7500 PCR system; ABI) in duplicate in 96-well plates with a final sample volume of 10 μL, including 1× universal PCR master mix (TaqMan; ABI), 25 ng DNA, and proper dilutions of probes/primers according to the manufacturer's instruction. Data were then collected (Absolute Quantification; SDS software, ver. 1.3.1, SDS, Cary, NC). 
Table 2.
 
Primers and Probes for the Quantization of the Target Gene Copy Numbers by Real-Time PCR
Table 2.
 
Primers and Probes for the Quantization of the Target Gene Copy Numbers by Real-Time PCR
Gene PCR Primers Hybridization Probes Amplicon Size (bp)
GSTM1 5′-CACCTGCATTCGTTCATGTGAC-3′ 6FAM-TTCAGTCCTGCCATGAGCAGGCACA-TAMRA 81
5′-CACCTGCATTCGTTCATGTGAC-3′
GSTT1 5′-AAGTCCCAGAGCACCTCACCTCC-3′ 6FAM-CACCATCCCCACCCTGTCTTCCA-TAMRA 82
5′-CAGTGTGCATCATTCTCATTGTGGC-3′
Copy number estimation was conducted by the ΔCt method (CopyCaller software, ver. 1.0; ABI). The detection of RNaseP, known to exist only in two copies in a diploid genome, was used as the calibrator to estimate the copy number of GSTM1 and GSTT1. 32,33,40 The calculation was performed by a maximum-likelihood algorithm built into the software. 
Statistical Analysis
A χ2 test was performed (Stata 8.0; Stata Corp., College Station, TX) to compare the genotype distributions of CNV between the cases and controls and estimate the odds ratio (OR) and 95% confidence interval (CI) of the comparison. P < 0.05 was considered to be statistically significant. 
Results
The assay afforded 100% call rates and 100% call accuracy (consistency of duplicate wells) for both genes. The readings of the genotypes were randomly distributed across the plates, thus excluding the possibility of batch effects. All samples with null genotypes showed a Ct value >39 for the target genes, whereas the Ct of RNaseP was ∼27. The mean ΔCt values for GSTT1*1/0, GSTT1*1/1, and GSTT1*>1/1 were 0.125169, −0.78088, and > −1.44014, respectively. The mean ΔCt for GSTM1*1/0, GSTM1*1/1, and GSTM1*>1/1 was −0.13458, −0.98676, and > −1.69163, respectively. 
The genotype distributions and ORs of GSTM1 and GSTT1 in patients with cataracts and control individuals are summarized in Table 3. The GSTM1 copy numbers were evenly distributed in the cases and controls. However, a significantly higher percentage with double deletion for GSTT1 (GSTT1*0/0 null) was found in the cataract patients in comparison with the control (P < 0.05). The GSTT1 null genotype conferred a significantly higher risk of developing ARC (OR = 1.56). Further analysis of the individuals with at least one GSTT1 allele deleted also revealed a significant impact on ARC risk (OR = 2.16, P < 0.01; Table 3). 
Table 3.
 
Association between GST Genotypes and Cataract Development
Table 3.
 
Association between GST Genotypes and Cataract Development
Gene/Copy Number Control n (%) 145 (100) Case n (%) 279 (100) P OR (95% CI)
GSTM1
    0/0 95 (65.5) 171 (61.3) 0.39* 0.83 (0.54–1.29)
    1/0 28 (19.3) 67 (24.0) 0.47† 0.78 (0.39–1.54)
    1/1 14 (9.7) 28 (10.0)
    >1/1 8 (5.5) 13 (4.7) 0.70* 0.84 (0.31–2.39)
GSTT1
    0/0 60 (41.4) 146 (52.3) 0.03* 1.56 (1.02–2.38)
    1/0 54 (37.2) 100 (35.9) 0.07† 0.57 (0.32–1.04)
    1/1 20 (13.8) 23 (8.2)
    >1/1 11 (7.6) 10 (3.6) 0.07* 0.45 (0.17–1.21)
    0/0 + 1/0 114 (78.6) 246 (88.2) 0.004† 2.16 (1.27–3.67)
After the stratification of the cases to the cortical, nuclear, and posterior subcapsular subtypes, no association was detected between the GSTT1 genotype and the nuclear type of ARC (Table 4). Consistent associations were observed between the GSTT1 genotype and the cortical type of ARC. The individuals with at least one deleted GSTT1 allele had a 4.81-fold increased risk of cortical ARC (P < 0.001), whereas individuals with GSTT1 >1/1 had a lower risk of the disease (OR = 0.19, P < 0.05; Table 4). There was no consistent association between GSTT1 CNV and posterior subcapsular cataract (Table 4). 
Table 4.
 
Association between GSTT1 Genotypes and the Subtypes of ARC
Table 4.
 
Association between GSTT1 Genotypes and the Subtypes of ARC
Copy Number Control n (%) 145 Cortical Nuclear Posterior Subcapsular
n (%) 131 (100) OR (95% CI) P n (%) 70 (100) OR (95% CI) P n (%) 78 (100) OR (95% CI) P
0/0 60 (41.4) 67 (51.2) 1.48 (0.92–2.39) 0.10* 33 (47.2) 1.26 (0.68–2.33) 0.42* 46 (59.0) 2.04 (1.16–3.56) 0.01*
1/0 54 (37.2) 57 (43.5) 4.98 (1.80–13.53) 0.0002** 21 (30.0) 0.80 (0.37–1.75) 0.31** 22 (28.2) 1.34 (0.57–3.19) 0.5**
1/1 20 (13.8) 5 (3.8) 12 (17.1) 6 (7.7)
>1/1 11 (7.6) 2 (1.5) 0.19 (0.04–0.87) 0.018* 4 (5.7) 0.74 (0.23–2.41) 0.61* 4 (5.1) 0.66 (0.20–2.14) 0.48*
0/0 + 1/0 114 (78.6) 124 (94.7) 4.81 (2.04–11.37) 0.0001** 54 (77.2) 0.92 (0.46–1.82) 0.81** 68 (87.2) 1.85 (0.85–4.01) 0.12**
Discussion
In this study, we found an association between CNV in GSTT1, but not in GSTM1, and ARC susceptibility. This result was not in agreement with previous studies which reported a more significant impact for CNV in GSTM1. Moreover, the GSTT1 association with ARC was more closely linked to the cortical type of the disease. The novel genotyping method adopted in this study discriminated between carriers of one or multiple copies of the genes, which provided more insight into the impact of CNVs in GSTT1/GSTM1 on ARC susceptibility. Our data show that GSTT1 >1/1 was protective against the development of the cortical type of ARC. 
Even though we tried to balance the possible confounding factors between the cases and controls, significant differences remained between the sexes, smoking, drinking, and hypertension. However, there was no report on the independent association of GST CNV with the individual's sex, drinking, or hypertension. There was also no report on the predisposition to smoking addiction in the presence of GST CNV, even though smoking often plays a role as a modifying factor in the association of GST CNV and various tumors. 41,42 Therefore, we believe that it is impossible for these imbalances to seriously distort the major conclusions of the study. 
Information on CNVs in different ethnic groups and subpopulation groups is seldom available. We anticipate that significant differences in the distribution of CNVs exist from population to population, mirroring the differences in the distribution of single nucleotide polymorphisms (SNPs), another common form of DNA sequence variation. The differences in CNV between ethnic groups could be one explanation for the discrepancy in the reported results on GST–ARC association. The minimum age of the control subjects in this study was 50 years, with an average age of 64.5 years. One characteristic of the residents older than 50 years in this geographic area is that they are less migratory and that they are the offspring of people who have lived here for generations due to unique geographic features, including the long distance from major transportation routes, geographic isolation due to rivers, and a conservative ideology. Because the study provided detailed CNV information for two genes in an ethnically homogenous population, it can serve as a reference for similar studies. Moreover, the data from a population-based study can minimize the selection bias. 
In Caucasians, enzymatic activity of GSTM1 and GSTT1 is absent in approximately 53.1% and 19.7% of the population, respectively. 43 The frequencies of homozygous deletions for GSTM1 and GSTT1 in a Korean population are 58.3% and 54.3%, respectively, 44 whereas the frequencies in a Japanese population are 51.3% and 54.0%, respectively. 45 We observed that 62.7% and 48.6% of the Han Chinese were homozygous for the GSTM1 and GSTT1 deletions, respectively. The frequency of the GSTT1 null genotype in the Han Chinese in our study was closer to that of the Japanese and Korean populations, but different from the Caucasian population. 
CNV in the human genome and its potential role in contributing to diseases has been gaining attention. 21,4649 In general, a gain in copy number results in increased gene expression. GSTs are important enzymes in the induction of endogenous and exogenous compounds. 40,50,51 They catalyze the nucleophilic addition of the thiol of GSH to many possibly harmful compounds, making them water-soluble so that they may be discharged more easily. 52 Oxidative damage of the lens is the major risk factor for the development of ARC. 5,10,11 The high GSH in the lens is believed to preserve the proper biological functions of thiols in structural proteins and enzymes, to detoxify xenobiotics, and thus to protect the lens from oxidative damage. 53 A significant decrease was recorded in GST activity in cataract lenses compared with age-matched normal lenses. 54  
In this study, we found that CNV with GSTT1 had a consistent association with cortical cataract but not other types of cataract. This finding may relate to the distinct distribution of GST activity in lens. The highest level of GST activity was found in the peripheral and equatorial regions, whereas the lowest activity was found in the nucleus. 54  
In conclusion, a clear association was established between the GSTT1 genotype and cataract susceptibility in a Han Chinese population. The association between GSTT1 CNV and ARC is more closely linked to cortical cataract. Individuals having at least one GSTT1 allele deleted will have a 4.81-fold increased risk of this subtype of the disease, whereas individuals with more than two copies of the GSTT1 allele will have a 5.26-fold (OR = 0.19) increased protection against the disease. 
Footnotes
 Supported by the Research Program of Nantong University and by the Key Medical Laboratory Program of Jiangsu Province, China.
Footnotes
 Disclosure: J. Zhou, None; J. Hu, None; H. Guan, None
References
Foster A Resnikoff S . The impact of Vision 2020 on global blindness. Eye. 2005;19:1133–1135. [CrossRef] [PubMed]
Asbell PA Dualan I Mindel J . Age-related cataract. Lancet. 2005;365:599–609. [CrossRef] [PubMed]
Livingston PM Carson CA Taylor HR . The epidemiology of cataract: a review of the literature. Ophthalmic Epidemiol. 1995;2:151–164. [CrossRef] [PubMed]
Reddy MA Francis PJ Berry V Bhattacharya SS Moore AT . Molecular genetic basis of inherited cataract and associated phenotypes. Surv Ophthalmol. 2004;49:300–315. [CrossRef] [PubMed]
Hejtmancik JF Kantorow M . Molecular genetics of age-related cataract. Exp Eye Res. 2004;79:3–9. [CrossRef] [PubMed]
Congdon N Broman KW Lai H . Nuclear cataract shows significant familial aggregation in an older population after adjustment for possible shared environmental factors. Invest Ophthalmol Vis Sci. 2004;45:2182–2186. [CrossRef] [PubMed]
Iyengar SK Klein BE Klein R . Identification of a major locus for age-related cortical cataract on chromosome 6p12–q12 in the Beaver Dam Eye Study. Proc Natl Acad Sci U S A. 2004;101:14485–14490. [CrossRef] [PubMed]
Bhagyalaxmi SG Srinivas P Barton KA . A novel mutation (F71L) in alphaA-crystallin with defective chaperone-like function associated with age-related cataract. Biochim Biophys Acta. 2009;1792:974–981. [CrossRef] [PubMed]
Shiels A Bennett TM Knopf HL . The EPHA2 gene is associated with cataracts linked to chromosome 1p. Mol Vis. 2008;14:2042–2055. [PubMed]
Truscott RJ . Age-related nuclear cataract: a lens transport problem. Ophthalmic Res. 2000;32:185–194. [CrossRef] [PubMed]
Marsili S Salganik RI Albright CD . Cataract formation in a strain of rats selected for high oxidative stress. Exp Eye Res. 2004;79:595–612. [CrossRef] [PubMed]
Pak JH Kim TI Joon KM . Reduced expression of 1-cys peroxiredoxin in oxidative stress-induced cataracts. Exp Eye Res. 2006;82:899–906. [CrossRef] [PubMed]
Lou MF . Redox regulation in the lens. Prog Retin Eye Res. 2003;22:657–682. [CrossRef] [PubMed]
Yan H Harding JJ Xing K Lou MF . Revival of glutathione reductase in human cataractous and clear lens extracts by thioredoxin and thioredoxin reductase, in conjunction with alpha-crystallin or thioltransferase. Curr Eye Res. 2007;32:455–463. [CrossRef] [PubMed]
Hayes JD Strange RC . Glutathione S-transferase polymorphisms and their biological consequences. Pharmacology. 2000;61:154–166. [CrossRef] [PubMed]
Board PG Baker RT Chelvanayagam G Jermiin LS . Zeta, a novel class of glutathione transferases in a range of species from plants to humans. Biochem J. 1997;328:929–935. [PubMed]
Pemble S Schroeder KR Spencer SR . Human glutathione S-transferase theta (GSTT1): cDNA cloning and the characterization of a genetic polymorphism. Biochem J. 1994;300:271–276. [PubMed]
McLellan RA Oscarson M Alexandrie AK . Characterization of a human glutathione S-transferase mu cluster containing a duplicated GSTM1 gene that causes ultrarapid enzyme activity. Mol Pharmacol. 1997;52:958–965. [PubMed]
Xu S Wang Y Roe B Pearson WR . Characterization of the human class Mu glutathione S-transferase gene cluster and the GSTM1 deletion. J Biol Chem. 1998;273:3517–3527. [CrossRef] [PubMed]
Sprenger R Schlagenhaufer R Kerb R . Characterization of the glutathione S-transferase GSTT1 deletion: discrimination of all genotypes by polymerase chain reaction indicates a trimodular genotype-phenotype correlation. Pharmacogenetics. 2000;10:557–565. [CrossRef] [PubMed]
McCarroll SA Altshuler DM . Copy-number variation and association studies of human disease. Nat Genet. 2007;39:S37–S42. [CrossRef] [PubMed]
Seidegard J Vorachek WR Pero RW Pearson WR . Hereditary differences in the expression of the human glutathione transferase active on trans-stilbene oxide are due to a gene deletion. Proc Natl Acad Sci U S A. 1988;85:7293–7297. [CrossRef] [PubMed]
Engel LS Taioli E Pfeiffer R . Pooled analysis and meta-analysis of glutathione S-transferase M1 and bladder cancer: a HuGE review. Am J Epidemiol. 2002;156:95–109. [CrossRef] [PubMed]
Ye Z Song H Higgins JP Pharoah P Danesh J . Five glutathione s-transferase gene variants in 23,452 cases of lung cancer and 30,397 controls: meta-analysis of 130 studies. PLoS Med. 2006;3:e91. [CrossRef] [PubMed]
Brasch-Andersen C Christiansen L Tan Q . Possible gene dosage effect of glutathione-S-transferases on atopic asthma: using real-time PCR for quantification of GSTM1 and GSTT1 gene copy numbers. Hum Mutat. 2004;24:208–214. [CrossRef] [PubMed]
Masetti S Botto N Manfredi S . Interactive effect of the glutathione S-transferase genes and cigarette smoking on occurrence and severity of coronary artery risk. J Mol Med. 2003;81:488–494. [CrossRef] [PubMed]
Alberti G Oguni M Podgor M . Glutathione S-transferase M1 genotype and age-related cataracts: lack of association in an Italian population. Invest Ophthalmol Vis Sci. 1996;37:1167–1173. [PubMed]
Juronen E Tasa G Veromann S . Polymorphic glutathione S-transferases as genetic risk factors for senile cortical cataract in Estonians. Invest Ophthalmol Vis Sci. 2000;41:2262–2267. [PubMed]
Pi J Bai Y Zheng Q . A study on relationship between glutathione S-transferase mu gene deletion and senile cataract susceptibility (in Chinese). Zhonghua Yan Ke Za Zhi. 1996;32:224–226. [PubMed]
Hao Y He S Gu Z . Relationship between GSTM1 genotype and susceptibility to senile cataract (in Chinese). Zhonghua Yan Ke Za Zhi. 1999;35:104–106. [PubMed]
Guven M Unal M Sarici A . Glutathione-S-transferase M1 and T1 genetic polymorphisms and the risk of cataract development: a study in the Turkish population. Curr Eye Res. 2007;32:447–454. [CrossRef] [PubMed]
Bediaga NG Alfonso-Sanchez MA de Renobales M Rocandio AM Arroyo M Pancorbo MM . GSTT1 and GSTM1 gene copy number analysis in paraffin-embedded tissue using quantitative real-time PCR. Anal Biochem. 2008;378:221–223. [CrossRef] [PubMed]
Norskov MS Frikke-Schmidt R Loft S Tybjaerg-Hansen A . High-throughput genotyping of copy number variation in glutathione S-transferases M1 and T1 using real-time PCR in 20,687 individuals. Clin Biochem. 2009;42:201–209. [CrossRef] [PubMed]
Li L Guan H Xun P Zhou J Gu H . Prevalence and causes of visual impairment among the elderly in Nantong, China. Eye (Lond). 2008;22:1069–1075. [CrossRef] [PubMed]
Li L Guan HJ Zhou JB . A cross-sectional survey of blindness and low vision among adults aged 60 years and above in Xinchengqiao Blocks, Nantong (in Chinese). Zhonghua Yan Ke Za Zhi. 2006;42:802–807. [PubMed]
Li T He T Tan X . Prevalence of age-related cataract in high-selenium areas of China. Biol Trace Elem Res. 2009;128:1–7. [CrossRef] [PubMed]
Okano Y Asada M Fujimoto A . A genetic factor for age-related cataract: identification and characterization of a novel galactokinase variant, “Osaka,” in Asians. Am J Hum Genet. 2001;68:1036–1042. [CrossRef] [PubMed]
Chylack LTJr Leske MC McCarthy D . Lens opacities classification system II (LOCS II). Arch Ophthalmol. 1989;107:991–997. [CrossRef] [PubMed]
Yang X Hu J Zhang J Guan H . Polymorphisms in CFH, HTRA1 and CX3CR1 confer risk to exudative age-related macular degeneration in Han Chinese. Br J Ophthalmol. In press.
Tsuchida S Sato K . Glutathione transferases and cancer. Crit Rev Biochem Mol Biol. 1992;27:337–384. [CrossRef] [PubMed]
Singh M Shah PP Singh AP . Association of genetic polymorphisms in glutathione S-transferases and susceptibility to head and neck cancer. Mutat Res. 2008;638:184–194. [CrossRef] [PubMed]
Agalliu I Langeberg WJ Lampe JW Salinas CA Stanford JL . Glutathione S-transferase M1, T1, and P1 polymorphisms and prostate cancer risk in middle-aged men. Prostate. 2006;66:146–156. [CrossRef] [PubMed]
Garte S Gaspari L Alexandrie AK . Metabolic gene polymorphism frequencies in control populations. Cancer Epidemiol Biomarkers Prev. 2001;10:1239–1248. [PubMed]
Cho HJ Lee SY Ki CS Kim JW . GSTM1, GSTT1 and GSTP1 polymorphisms in the Korean population. J Korean Med Sci. 2005;20:1089–1092. [CrossRef] [PubMed]
Naoe T Takeyama K Yokozawa T . Analysis of genetic polymorphism in NQO1, GST-M1, GST-T1, and CYP3A4 in 469 Japanese patients with therapy-related leukemia/myelodysplastic syndrome and de novo acute myeloid leukemia. Clin Cancer Res. 2000;6:4091–4095. [PubMed]
Kehrer-Sawatzki H . What a difference copy number variation makes. Bioessays. 2007;29:311–313. [CrossRef] [PubMed]
Redon R Ishikawa S Fitch KR . Global variation in copy number in the human genome. Nature. 2006;444:444–454. [CrossRef] [PubMed]
Henrichsen CN Chaignat E Reymond A . Copy number variants, diseases and gene expression. Hum Mol Genet. 2009;18:R1–R8. [CrossRef] [PubMed]
Aitman TJ Dong R Vyse TJ . Copy number polymorphism in Fcgr3 predisposes to glomerulonephritis in rats and humans. Nature. 2006;439:851–855. [CrossRef] [PubMed]
Wormhoudt LW Commandeur JN Vermeulen NP . Genetic polymorphisms of human N-acetyltransferase, cytochrome P450, glutathione-S-transferase, and epoxide hydrolase enzymes: relevance to xenobiotic metabolism and toxicity. Crit Rev Toxicol. 1999;29:59–124. [CrossRef] [PubMed]
Rebbeck TR . Molecular epidemiology of the human glutathione S-transferase genotypes GSTM1 and GSTT1 in cancer susceptibility. Cancer Epidemiol Biomarkers Prev. 1997;6:733–743. [PubMed]
Mannervik B Danielson UH . Glutathione transferases: structure and catalytic activity. CRC Crit Rev Biochem. 1988;23:283–337. [CrossRef] [PubMed]
Lou MF . Thiol regulation in the lens. J Ocul Pharmacol Ther. 2000;16:137–148. [CrossRef] [PubMed]
Rao GN Sadasivudu B Cotlier E . Studies on glutathione S-transferase, glutathione peroxidase and glutathione reductase in human normal and cataractous lenses. Ophthalmic Res. 1983;15:173–179. [CrossRef] [PubMed]
Table 1.
 
Demographics of Study Participants
Table 1.
 
Demographics of Study Participants
Group n Sex Age (y) Smoking n (%) Drinking n (%) Hypertension n (%) Blood Glucose (mmol/L)
Male n (%) Female n (%) Mean ± SD Range
Control 145 72 (49.7) 73 (50.3) 64.5 ± 4.2 59–82 32 (22.1) 40 (27.6) 38 (26.2) 4.9 ± 3.1
ARC 279 103 (36.9)* 176 (63.1)* 69.0 ± 8.4 50–92 89 (31.9)* 51 (18.3)* 109 (39.1)* 5.1 ± 4.0
Table 2.
 
Primers and Probes for the Quantization of the Target Gene Copy Numbers by Real-Time PCR
Table 2.
 
Primers and Probes for the Quantization of the Target Gene Copy Numbers by Real-Time PCR
Gene PCR Primers Hybridization Probes Amplicon Size (bp)
GSTM1 5′-CACCTGCATTCGTTCATGTGAC-3′ 6FAM-TTCAGTCCTGCCATGAGCAGGCACA-TAMRA 81
5′-CACCTGCATTCGTTCATGTGAC-3′
GSTT1 5′-AAGTCCCAGAGCACCTCACCTCC-3′ 6FAM-CACCATCCCCACCCTGTCTTCCA-TAMRA 82
5′-CAGTGTGCATCATTCTCATTGTGGC-3′
Table 3.
 
Association between GST Genotypes and Cataract Development
Table 3.
 
Association between GST Genotypes and Cataract Development
Gene/Copy Number Control n (%) 145 (100) Case n (%) 279 (100) P OR (95% CI)
GSTM1
    0/0 95 (65.5) 171 (61.3) 0.39* 0.83 (0.54–1.29)
    1/0 28 (19.3) 67 (24.0) 0.47† 0.78 (0.39–1.54)
    1/1 14 (9.7) 28 (10.0)
    >1/1 8 (5.5) 13 (4.7) 0.70* 0.84 (0.31–2.39)
GSTT1
    0/0 60 (41.4) 146 (52.3) 0.03* 1.56 (1.02–2.38)
    1/0 54 (37.2) 100 (35.9) 0.07† 0.57 (0.32–1.04)
    1/1 20 (13.8) 23 (8.2)
    >1/1 11 (7.6) 10 (3.6) 0.07* 0.45 (0.17–1.21)
    0/0 + 1/0 114 (78.6) 246 (88.2) 0.004† 2.16 (1.27–3.67)
Table 4.
 
Association between GSTT1 Genotypes and the Subtypes of ARC
Table 4.
 
Association between GSTT1 Genotypes and the Subtypes of ARC
Copy Number Control n (%) 145 Cortical Nuclear Posterior Subcapsular
n (%) 131 (100) OR (95% CI) P n (%) 70 (100) OR (95% CI) P n (%) 78 (100) OR (95% CI) P
0/0 60 (41.4) 67 (51.2) 1.48 (0.92–2.39) 0.10* 33 (47.2) 1.26 (0.68–2.33) 0.42* 46 (59.0) 2.04 (1.16–3.56) 0.01*
1/0 54 (37.2) 57 (43.5) 4.98 (1.80–13.53) 0.0002** 21 (30.0) 0.80 (0.37–1.75) 0.31** 22 (28.2) 1.34 (0.57–3.19) 0.5**
1/1 20 (13.8) 5 (3.8) 12 (17.1) 6 (7.7)
>1/1 11 (7.6) 2 (1.5) 0.19 (0.04–0.87) 0.018* 4 (5.7) 0.74 (0.23–2.41) 0.61* 4 (5.1) 0.66 (0.20–2.14) 0.48*
0/0 + 1/0 114 (78.6) 124 (94.7) 4.81 (2.04–11.37) 0.0001** 54 (77.2) 0.92 (0.46–1.82) 0.81** 68 (87.2) 1.85 (0.85–4.01) 0.12**
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×