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1.  Polymorphisms in ARMS2/HTRA1 and Complement Genes and Age-Related Macular Degeneration in India: Findings from the INDEYE Study 
Purpose.
Association between genetic variants in complement factor H (CFH), factor B (CFB), component 2 (C2), and in the ARMS2/HTRA1 region with age-related macular degeneration (AMD) comes mainly from studies of European ancestry and case-control studies of late-stage disease. We investigated associations of both early and late AMD with these variants in a population-based study of people aged 60 years and older in India.
Methods.
Fundus images were graded using the Wisconsin Age-Related Maculopathy Grading System and participants assigned to one of four mutually exclusive stages based on the worse affected eye (0 = no AMD, 1–3 = early AMD, 4 = late AMD). Multinomial logistic regression was used to derive risk ratios (RR) accounting for sampling method and adjusting for age, sex, and study center.
Results.
Of 3569 participants, 53.2% had no signs of AMD, 45.6% had features of early AMD, and 1.2% had late AMD. CFH (rs1061170), C2 (rs547154), or CFB (rs438999) was not associated with early or late AMD. In the ARMS2 locus, rs10490924 was associated with both early (adjusted RR 1.22, 95% confidence interval [CI]: 1.13–1.33, P < 0.0001) and late AMD (adjusted RR 1.81, 95% CI: 1.15–2.86; P = 0.01); rs2672598 was associated only with early AMD (adjusted RR 1.12, 95% CI: 1.02–1.23; P = 0.02); rs10490923 was not associated with early or late AMD.
Conclusions.
Two variants in ARMS2/HTRA1 were associated with increased risk of early AMD, and for one of these, the increased risk was also evident for late AMD. The study provides new insights into the role of these variants in early stages of AMD in India.
We report results from a genetic association study of early AMD in an Indian population. Two variants in the ARMS/HTRA1 region were associated with early AMD but variants in C2, CFH, and CFB were not.
doi:10.1167/iovs.12-10073
PMCID: PMC3490538  PMID: 23060141
2.  Evidence of association of APOE with age-related macular degeneration - a pooled analysis of 15 studies 
Human mutation  2011;32(12):1407-1416.
Age-related macular degeneration (AMD) is the most common cause of incurable visual impairment in high-income countries. Previous studies report inconsistent associations between AMD and apolipoprotein E (APOE), a lipid transport protein involved in low-density cholesterol modulation. Potential interaction between APOE and sex, and smoking status, has been reported. We present a pooled analysis (n=21,160) demonstrating associations between late AMD and APOε4 (OR=0.72 per haplotype; CI: 0.65–0.74; P=4.41×10−11) and APOε2 (OR=1.83 for homozygote carriers; CI: 1.04–3.23; P=0.04), following adjustment for age-group and sex within each study and smoking status. No evidence of interaction between APOE and sex or smoking was found. Ever smokers had significant increased risk relative to never smokers for both neovascular (OR=1.54; CI: 1.38–1.72; P=2.8×10−15) and atrophic (OR=1.38; CI: 1.18–1.61; P=3.37×10−5) AMD but not early AMD (OR=0.94; CI: 0.86–1.03; P=0.16), implicating smoking as a major contributing factor to disease progression from early signs to the visually disabling late forms. Extended haplotype analysis incorporating rs405509 did not identify additional risks beyondε2 and ε4 haplotypes. Our expanded analysis substantially improves our understanding of the association between the APOE locus and AMD. It further provides evidence supporting the role of cholesterol modulation, and low-density cholesterol specifically, in AMD disease etiology.
doi:10.1002/humu.21577
PMCID: PMC3217135  PMID: 21882290
age-related macular degeneration; AMD; apolipoprotein E; APOE; case-control association study
3.  EPHA2 Polymorphisms and Age-Related Cataract in India 
PLoS ONE  2012;7(3):e33001.
Objective
We investigated whether previously reported single nucleotide polymorphisms (SNPs) of EPHA2 in European studies are associated with cataract in India.
Methods
We carried out a population-based genetic association study. We enumerated randomly sampled villages in two areas of north and south India to identify people aged 40 and over. Participants attended a clinical examination including lens photography and provided a blood sample for genotyping. Lens images were graded by the Lens Opacification Classification System (LOCS III). Cataract was defined as a LOCS III grade of nuclear ≥4, cortical ≥3, posterior sub-capsular (PSC) ≥2, or dense opacities or aphakia/pseudophakia in either eye. We genotyped SNPs rs3754334, rs7543472 and rs11260867 on genomic DNA extracted from peripheral blood leukocytes using TaqMan assays in an ABI 7900 real-time PCR. We used logistic regression with robust standard errors to examine the association between cataract and the EPHA2 SNPs, adjusting for age, sex and location.
Results
7418 participants had data on at least one of the SNPs investigated. Genotype frequencies of controls were in Hardy-Weinberg Equilibrium (p>0.05). There was no association of rs3754334 with cataract or type of cataract. Minor allele homozygous genotypes of rs7543472 and rs11260867 compared to the major homozygote genotype were associated with cortical cataract, Odds ratio (OR) = 1.8, 95% Confidence Interval (CI) (1.1, 3.1) p = 0.03 and 2.9 (1.2, 7.1) p = 0.01 respectively, and with PSC cataract, OR = 1.5 (1.1, 2.2) p = 0.02 and 1.8 (0.9, 3.6) p = 0.07 respectively. There was no consistent association of SNPs with nuclear cataract or a combined variable of any type of cataract including operated cataract.
Conclusions
Our results in the Indian population agree with previous studies of the association of EPHA2 variants with cortical cataracts. We report new findings for the association with PSC which is particularly prevalent in Indians.
doi:10.1371/journal.pone.0033001
PMCID: PMC3297613  PMID: 22412971
4.  Prevalence and Risk Factors for Vitamin C Deficiency in North and South India: A Two Centre Population Based Study in People Aged 60 Years and Over 
PLoS ONE  2011;6(12):e28588.
Background
Studies from the UK and North America have reported vitamin C deficiency in around 1 in 5 men and 1 in 9 women in low income groups. There are few data on vitamin C deficiency in resource poor countries.
Objectives
To investigate the prevalence of vitamin C deficiency in India.
Design
We carried out a population-based cross-sectional survey in two areas of north and south India. Randomly sampled clusters were enumerated to identify people aged 60 and over. Participants (75% response rate) were interviewed for tobacco, alcohol, cooking fuel use, 24 hour diet recall and underwent anthropometry and blood collection. Vitamin C was measured using an enzyme-based assay in plasma stabilized with metaphosphoric acid. We categorised vitamin C status as deficient (<11 µmol/L), sub-optimal (11–28 µmol/L) and adequate (>28 µmol/L). We investigated factors associated with vitamin C deficiency using multivariable Poisson regression.
Results
The age, sex and season standardized prevalence of vitamin C deficiency was 73.9% (95% confidence Interval, CI 70.4,77.5) in 2668 people in north India and 45.7% (95% CI 42.5,48.9) in 2970 from south India. Only 10.8% in the north and 25.9% in the south met the criteria for adequate levels. Vitamin C deficiency varied by season, and was more prevalent in men, with increasing age, users of tobacco and biomass fuels, in those with anthropometric indicators of poor nutrition and with lower intakes of dietary vitamin C.
Conclusions
In poor communities, such as in our study, consideration needs to be given to measures to improve the consumption of vitamin C rich foods and to discourage the use of tobacco.
doi:10.1371/journal.pone.0028588
PMCID: PMC3232233  PMID: 22163038
5.  Inverse Association of Vitamin C with Cataract in Older People in India 
Ophthalmology  2011;118(10):1958-1965.e2.
Objective
To examine the association between vitamin C and cataract in the Indian setting.
Design
Population-based cross-sectional analytic study.
Participants
A total of 5638 people aged ≥60 years.
Methods
Enumeration of randomly sampled villages in 2 areas of north and south India to identify people aged ≥60 years. Participants were interviewed for socioeconomic and lifestyle factors (tobacco, alcohol, household cooking fuel, work, and diet); attended a clinical examination, including lens photography; and provided a blood sample for antioxidant analysis. Plasma vitamin C was measured using an enzyme-based assay in plasma stabilized with metaphosphoric acid, and other antioxidants were measured by reverse-phase high-pressure liquid chromatography.
Main Outcome Measures
Cataract and type of cataract were graded from digital lens images using the Lens Opacity Classification System III (LOCS III), and cataract was classified from the grade in the worse eye of ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any cataract was defined as any unoperated or operated cataract.
Results
Of 7518 enumerated people, 5638 (75%) provided data on vitamin C, antioxidants, and potential confounders. Vitamin C was inversely associated with cataract (adjusted odds ratio [OR] for highest to lowest quartile = 0.61; 95% confidence interval (CI), 0.51–0.74; P=1.1×10−6). Inclusion of other antioxidants in the model (lutein, zeaxanthin, retinol, β-carotene, and α-tocopherol) made only a small attenuation to the result (OR 0.68; 95% CI, 0.57–0.82; P < 0.0001). Similar results were seen with vitamin C by type of cataract: nuclear cataract (adjusted OR 0.66; CI, 0.54–0.80; P < 0.0001), cortical cataract (adjusted OR 0.70; CI, 0.54–0.90; P < 0.002), and PSC (adjusted OR 0.58; CI, 0.45–0.74; P < 0.00003). Lutein, zeaxanthin, and retinol were significantly inversely associated with cataract, but the associations were weaker and not consistently observed by type of cataract. Inverse associations were also observed for dietary vitamin C and cataract.
Conclusions
We found a strong association with vitamin C and cataract in a vitamin C–depleted population.
Financial Disclosure(s)
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
doi:10.1016/j.ophtha.2011.03.016
PMCID: PMC3185206  PMID: 21705085
6.  Prevalence of Cataract in an Older Population in India 
Ophthalmology  2011;118(2-19):272-278.e2.
Purpose
To describe the prevalence of cataract in older people in 2 areas of north and south India.
Design
Population-based, cross-sectional study.
Participants
Randomly sampled villages were enumerated to identify people aged ≥60 years. Of 7518 enumerated people, 78% participated in a hospital-based ophthalmic examination.
Methods
The examination included visual acuity measurement, dilatation, and anterior and posterior segment examination. Digital images of the lens were taken and graded by type and severity of opacity using the Lens Opacity Classification System III (LOCS III).
Main Outcome Measures
Age- and gender-standardized prevalence of cataract and 95% confidence intervals (CIs). We defined type of cataract based on the LOCS III grade in the worse eye of: ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any unoperated cataract was based on these criteria or ungradable dense opacities. Any cataract was defined as any unoperated or operated cataract.
Results
The prevalence of unoperated cataract in people aged ≥60 was 58% in north India (95% CI, 56–60) and 53% (95% CI, 51–55) in south India (P = 0.01). Nuclear cataract was the most common type: 48% (95% CI, 46–50) in north India and 38% (95% CI, 37–40) in south India (P<0.0001); corresponding figures for PSC were 21% (95% CI, 20–23) and 17% (95% CI, 16–19; P = 0.003), respectively, and for cortical cataract 7.6% (95% CI, 7–9) and 10.2% (95% CI, 9–11; P<0.004). Bilateral aphakia/pseudophakia was slightly higher in the south (15.5%) than in the north (13.2%; P<0.03). The prevalence of any cataracts was similar in north (73.8%) and south India (71.8%). The prevalence of unoperated cataract increased with age and was higher in women than men (odds ratio [OR], 1.8). Aphakia/pseudophakia was also more common in women, either unilateral (OR, 1.2; P<0.02) or bilateral (OR, 1.3; P<0.002).
Conclusions
We found high rates of unoperated cataract in older people in north and south India. Posterior subcapsular cataract was more common than in western studies. Women had higher rates of cataract, which was not explained by differential access to surgery.
Financial Disclosure(s)
The authors have no proprietary or commercial interest in any of the materials discussed in this article.
doi:10.1016/j.ophtha.2010.05.020
PMCID: PMC3146699  PMID: 20801514
7.  Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis 
BMC Ophthalmology  2010;10:31.
Background
Age-related macular degeneration (AMD) is the leading cause of blindness in Western countries. Numerous risk factors have been reported but the evidence and strength of association is variable. We aimed to identify those risk factors with strong levels of evidence which could be easily assessed by physicians or ophthalmologists to implement preventive interventions or address current behaviours.
Methods
A systematic review identified 18 prospective and cross-sectional studies and 6 case control studies involving 113,780 persons with 17,236 cases of late AMD that included an estimate of the association between late AMD and at least one of 16 pre-selected risk factors. Fixed-effects meta-analyses were conducted for each factor to combine odds ratio (OR) and/or relative risk (RR) outcomes across studies by study design. Overall raw point estimates of each risk factor and associated 95% confidence intervals (CI) were calculated.
Results
Increasing age, current cigarette smoking, previous cataract surgery, and a family history of AMD showed strong and consistent associations with late AMD. Risk factors with moderate and consistent associations were higher body mass index, history of cardiovascular disease, hypertension, and higher plasma fibrinogen. Risk factors with weaker and inconsistent associations were gender, ethnicity, diabetes, iris colour, history of cerebrovascular disease, and serum total and HDL cholesterol and triglyceride levels.
Conclusions
Smoking, previous cataract surgery and a family history of AMD are consistent risk factors for AMD. Cardiovascular risk factors are also associated with AMD. Knowledge of these risk factors that may be easily assessed by physicians and general ophthalmologists may assist in identification and appropriate referral of persons at risk of AMD.
doi:10.1186/1471-2415-10-31
PMCID: PMC3009619  PMID: 21144031
8.  An Ecological Correlation Study of Late Age-Related Macular Degeneration and the Complement Factor H Y402H Polymorphism 
Based on published data, this ecological correlation study showed evidence to support the hypothesis that variation in the risk allele frequency of the Y402H polymorphism across ethnicities explains variation in prevalence of late AMD when data on people of African ancestry are excluded.
Purpose.
To investigate whether variation in the distribution of the risk allele frequency of the Y402H single-nucleotide polymorphism (SNP) across various ethnicities and geographic regions reflects differences in the prevalence of late age-related macular degeneration (AMD) in those ethnicities.
Methods.
Published data were obtained via a systematic search. Study samples were grouped into clusters by ethnicity and geographic location and the Spearman correlation coefficient of the prevalence of late AMD and risk allele frequencies was calculated across clusters.
Results.
Across all ethnicities, AMD prevalence was seen to increase with age. Populations of European descent had both higher risk allele frequencies and prevalence of late AMD than did Japanese, Chinese, and Hispanic descendants. Results for African descendants were anomalous: although allele frequency was similar to that in European populations, the age-specific prevalence of late AMD was considerably lower. The correlation coefficient for the association between allele frequency and AMD prevalence was 0.40 (95% confidence interval [CI] = −0.36 to 0.84, P = 0.28) in all populations combined and 0.71 (95% CI = 0.02–0.94, P = 0.04) when people of African descent were excluded.
Conclusions.
Evidence was found at the population level to support a positive association between the Y204H risk allele and the prevalence of AMD after exclusion of studies undertaken on persons of African ancestry. Data in African, Middle Eastern, and South American populations are needed to provide a better understanding of the association of late AMD genetic risk across ethnicities.
doi:10.1167/iovs.09-4228
PMCID: PMC2868481  PMID: 20042653
9.  Prevalence of Early and Late Age-Related Macular Degeneration in India: The INDEYE Study 
This large, two-center, population-based study provides estimates of the prevalence of age-related macular degeneration in India.
Purpose.
To estimate the prevalence of early and late age-related macular degeneration (AMD) in India.
Methods.
Of 7518 people aged 60 years and older identified from randomly sampled villages in North and South India, 5853 (78%) attended an eye examination including fundus photography. Fundus images were graded according to the Wisconsin Age-Related Maculopathy Grading System.
Results.
Fundus images were ungradable in 1587 people, mainly because of cataract. People 80 years of age and older were less likely to attend the eye examination and more likely to have ungradable images. For ages 60 to 79 years, the percent prevalence (95% confidence interval [CI]) were late AMD 1.2 (0.8–1.5); and early AMD: grade 1 (soft distinct drusen or pigmentary irregularities), 39.3 (37.2–41.5); grade 2 (soft distinct drusen with pigmentary irregularities or soft indistinct or reticular drusen), 6.7 (5.8–7.6); and grade 3 (soft indistinct or reticular drusen with pigmentary irregularities), 0.2 (0.1–0.4). For ages 80 and older, the respective percent prevalence was: late AMD, 2.5 (0.4–4.7); and early AMD: grade 1, 43.1(35.7–50.6); grade 2, 8.1 (4.3–12.0); and grade 3, 0.5 (0–1.5).
Conclusions.
The prevalence of early AMD (grades 1 and 2) is similar to that observed in Western populations, but grade 3 appears to be lower. The prevalence of late AMD is comparable to that in Western populations in the age group 60 to 79 years. It is likely that the prevalence in the 80 and older age group is underestimated.
doi:10.1167/iovs.09-4114
PMCID: PMC2868454  PMID: 19696177

Results 1-9 (9)