Cataract is one of the most common causes of visual impairment and blindness all over the world. 80% of cataract is age-related cataract (ARC), which is classified as cortical cataract (CC), nuclear cataract (NC), or posterior subcapsular cataract (PSC), according to the location of the opacity in the lens [
There are many cellular defense mechanisms that protect the human lens from oxidative damage. The glutathione S-transferase (GST) is one of the detoxification enzyme systems and plays important role in inactivating endogenous and exogenous toxic products under oxidative stress. The GST isoenzymes have been reported to express classes, mu, theta, and pi, in human lens tissue [
Possible association between the
We conducted a comprehensive systematic search to identify relevant studies from Medline, Embase, PubMed, Web of Science, and China National Knowledge Infrastructure using keyword combinations: “glutathione S-transferase or
Studies that met all the following criteria were regarded eligible: (1) case-control study, (2) investigation of the association between
The association between
Flow diagram of studies included in this meta-analysis is provided in Figure
Characteristics of studies included in the meta-analysis.
First author | Year | Ethnicity (country) | Sample size | Number of null genotypes | References | Quality score | ||
---|---|---|---|---|---|---|---|---|
Cases | Controls | Cases | Controls | |||||
|
||||||||
Pi | 1996 | Asian (China) | 59 | 112 | 41 | 57 | [ |
18 |
Hao | 1999 | Asian (China) | 77 | 76 | 41 | 35 | [ |
17 |
Xu | 2007 | Asian (China) | 120 | 118 | 81 | 60 | [ |
19 |
Zhou | 2010 | Asian (China) | 279 | 145 | 171 | 95 | [ |
29 |
Jiang | 2012 | Asian (China) | 422 | 312 | 176 | 173 | [ |
31 |
Sekine | 1995 | Asian (Japan) | 138 | 62 | 101 | 30 | [ |
20 |
Sireesha | 2012 | Caucasian (India) | 455 | 205 | 177 | 94 | [ |
32 |
Alberti | 1996 | Caucasian (Italy) | 202 | 98 | 99 | 49 | [ |
23 |
Juronen | 2000 | Caucasian (Estonia) | 503 | 202 | 240 | 111 | [ |
25 |
Saadat | 2004 | Caucasian (Iran) | 150 | 150 | 90 | 58 | [ |
25 |
Saadat | 2006 | Caucasian (Iran) | 95 | 95 | 56 | 36 | [ |
23 |
Güven | 2007 | Caucasian (Turkey) | 195 | 136 | 105 | 58 | [ |
29 |
Abdel Azeem | 2009 | Caucasian (Egypt) | 53 | 73 | 23 | 46 | [ |
22 |
Saadat | 2012 | Caucasian (Iran) | 186 | 195 | 104 | 89 | [ |
26 |
Chandra | 2014 | Caucasian (India) | 131 | 126 | 43 | 68 | [ |
25 |
|
||||||||
Zhou | 2010 | Asian (China) | 279 | 145 | 146 | 60 | [ |
29 |
Jiang | 2012 | Asian (China) | 422 | 312 | 221 | 138 | [ |
31 |
Sireesha | 2012 | Caucasian (India) | 455 | 205 | 123 | 40 | [ |
32 |
Juronen | 2000 | Caucasian (Estonia) | 503 | 202 | 73 | 36 | [ |
25 |
Saadat | 2004 | Caucasian (Iran) | 150 | 150 | 49 | 46 | [ |
25 |
Güven | 2007 | Caucasian (Turkey) | 195 | 136 | 29 | 22 | [ |
29 |
Abdel Azeem | 2009 | Caucasian (Egypt) | 53 | 73 | 16 | 21 | [ |
22 |
Saadat | 2012 | Caucasian (Iran) | 186 | 195 | 49 | 57 | [ |
26 |
Chandra | 2014 | Caucasian (India) | 131 | 126 | 18 | 5 | [ |
25 |
Flow chart showing study selection procedure.
The forest plot of the
Forest plot of the association between
Subgroup analyses on ethnicity indicated that the association between
Ethnicity-based subgroup analysis of the correlation between
Subgroup analysis of the correlation between
Working place-based subgroup analysis of the correlation between
To investigate the association between profiles of
Subgroup analysis of the association between
Groups | Number of studies | Statistical method | OR (95% CI) |
|
References |
---|---|---|---|---|---|
|
|||||
All studies | 15 | Random | 1.161 (0.863–1.563) | 0.324 | [ |
Ethnicity: | |||||
Asian | 6 | Random | 1.372 (0.786–2.396) | 0.266 | [ |
Caucasian | 9 | Random | 1.053 (0.726–1.526) | 0.158 | [ |
Gender: | |||||
Female | 5 | Random | 1.016 (0.444–2.324) | 0.970 | [ |
Male | 5 | Random | 0.892 (0.582–1.365) | 0.598 | [ |
Subtype: | |||||
CC | 6 | Fixed | 0.713 (0.598–0.850) |
|
[ |
NC | 5 | Fixed | 0.887 (0.685–1.148) | 0.363 | [ |
PSC | 4 | Fixed | 1.042 (0.797–1.362) | 0.765 | [ |
MT | 3 | Random | 0.937 (0.510–1.722) | 0.834 | [ |
Environmental risk factors: | |||||
Outdoor | 2 | Fixed | 1.019 (0.511–2.034) | 0.957 | [ |
Indoor | 2 | Random | 2.062 (1.074–3.961) |
|
[ |
|
|||||
All studies | 9 | Fixed | 1.229 (1.057–1.429) |
|
[ |
Ethnicity: | |||||
Asian | 2 | Fixed | 1.442 (1.137–1.830) |
|
[ |
Caucasian | 7 | Fixed | 1.113 (0.830–1.492) | 0.474 | [ |
Gender: | |||||
Female | 5 | Fixed | 1.281 (0.972–1.687) | 0.078 | [ |
Male | 5 | Fixed | 1.288 (0.977–1.698) | 0.073 | [ |
Subtype: | |||||
CC | 5 | Fixed | 1.226 (0.999–1.504) | 0.051 | [ |
NC | 4 | Random | 0.921 (0.524–1.617) | 0.774 | [ |
PSC | 4 | Fixed | 1.421 (1.043–1.936) |
|
[ |
MT | 3 | Random | 1.209 (0.663–2.204) | 0.535 | [ |
|
6 | Fixed | 1.069 (0.843–1.356) | 0.581 | [ |
|
6 | Random | 1.005 (0.658–1.536) | 0.981 | [ |
|
|||||
|
5 | Random | 1.281 (0.840–1.954) | 0.250 | [ |
Funnel plots and Egger’s test were generated to evaluate potential publication bias for
Begg’s funnel plots of publication bias analyses. (a) Funnel plot of
Causality of age-related cataract is considered to be multifactorial, and oxidative stress and genetic factors are considered the major factors in its development. It has been noted that
Compared to Sun’s study, our study has some particular strength. First, we added four studies with large samples size, the absence of which might lead to a deviation in the results of Sun’s study. Second, given that GSTs play a vital role in detoxification of xenobiotics and protection of lens from the oxidative damage, we performed subgroup analysis based on the work place (outdoor/indoor) to investigate the possible contribution of
Inconsistent with the previous meta-analysis, our finding indicated that the
In our study,
Considering the role of
Gender differences have also been observed on the association between
Despite the fact that we made an accurate and comprehensive analysis, limitations still existed in our study. First, our meta-analysis only included studies with accessible full-text articles, in English or Chinese. Therefore, the absence of some otherwise eligible studies that were unpublished or reported in other languages could lead to some inevitable publication bias. Second, due to the lack of detailed data, subgroup analysis stratified by habits like smoking and alcohol consumption was not conducted. Third, the type and degree of opacification were classified using the lens opacities classification system II (LOCS II) or lens opacities classification system III (LOCS III). Difference of classified methods among the studies might have affected the results.
In summary, this study suggested that
The authors declare no conflict of interests regarding the publication of this paper.
The authors thank Jingjing Tong and Dazhi Fan for helpful comments.