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1.  Apolipoprotein E gene and age-related macular degeneration in a Chinese population 
Molecular Vision  2011;17:997-1002.
Purpose
To examine the association between apolipoprotein E (APOE) polymorphisms and age-related macular degeneration (AMD) in a Chinese population.
Methods
The study consisted of 712 subjects, including 201 controls, 363 cases with early AMD, and 148 cases with exudative AMD. Genomic DNA was extracted from venous blood leukocytes. Common allelic variants of APOE (ε2, ε3, and ε4) were analyzed by PCR and direct sequencing.
Results
APOE ε3ε3 was the most frequent genotype, with a frequency of 72.6% in controls, 72.5% in early AMD, and 70.3% in exudative AMD. Frequency of the ε2 allele was 6.7% in controls, 7.4% in early AMD, and 8.8% in exudative AMD. Frequency of the ε4 allele was 8.7% in controls, 7.7% in early AMD, and 7.8% in exudative AMD. No statistically significant difference in APOE genotype and allele frequency distribution was observed among controls, cases with early AMD, and cases with exudative AMD. For ε2 allele carriers, the odds ratio was 1.12 (95% confidence interval [CI], 0.65–1.93) for early AMD and 1.06 (95% CI, 0.53–2.10) for exudative AMD. For ε4 allele carriers, the odds ratio was 1.04 (95% CI, 0.61–1.75) for early AMD and 0.83 (95% CI, 0.42–1.62) for exudative AMD.
Conclusions
Our data provide no evidence to support an association of APOE polymorphisms with early or exudative AMD, suggesting that APOE is less likely to be a major AMD susceptibility gene in the Chinese population.
PMCID: PMC3084239  PMID: 21541275
2.  Cerebral white matter lesions are not associated with apoE genotype but with age and female sex in Alzheimer's disease 
Cerebral white matter lesions, such as leukoaraiosis, may be a result of damage from cerebral ischaemia, and may also be associated with the degenerative process in Alzheimer's disease. The apolipoprotein ε4 (apoε4) genotype is a genetic risk factor for both Alzheimer's disease and ischaemic brain damage through acceleration of atherosclerosis. The aim was to determine whether apoε4 may be related to the formation of cerebral white matter lesions in Alzheimer's disease. The association of apoE genotype, sex, age, and the presence of several vascular risk factors, with the presence of white matter lesions in 55patients clinically diagnosed with Alzheimer's disease was investigated. The cerebral white matter lesions were identified by T2 weighted MRI and classified on a 4 grade scale from no lesion to diffuse lesion. The odds ratio (OR) of the factors mentioned above to the presence of white matter lesions was determined and tested by Fisher's exact test. The association of the lesion grades with these factors was analysed by non-parametric tests. The apoE 4genotype was strongly associated with Alzheimer's disease (p=0.0001), but not associated with the presence or the degree of cerebral white matter lesions in Alzheimer's disease (OR=1.09, p>0.99). Aging (>70 years old) was a significant risk factor for white matter lesions (OR=7.2, p=0.0006) and age was significantly correlated with the lesion (p=0.0075). The OR of female sex to the lesion grades was 2.89 (p=0.084) and the lesion grade of female sex was significantly higher than that of the male sex (p=0.047). Other vascular risk factors were not significantly associated with the presence of white matter lesions. These findings suggest that there is a sex difference in white matter pathology in Alzheimer's disease.


doi:10.1136/jnnp.68.5.653
PMCID: PMC1736920  PMID: 10766901
3.  An Apolipoprotein E Variant may Protect against Age-Related Macular Degeneration through Cytokine Regulation 
Age-related macular degeneration (AMD) is the leading cause of visual impairment and blindness among the elderly in Western countries. Genetic factors, age, cigarette smoking, nutrition, and exposure to light have been identified as AMD risk factors. In this study, we investigated the association between ApoE C112R/R158C single nucleotide polymorphisms (which determine the E2, E3, and E4 isoforms) and age-related macular degeneration (AMD), and the mechanism underlying the association. Genomic DNA was extracted from 133 clinically screened controls, 94 volunteers with a younger mean age, 120 patients with advanced AMD, and 40 archived ocular AMD slides for single nucleotide polymorphism typing. The effects of recombinant ApoE isoforms on CCL2 (a chemokine), CX3CR1 (a chemokine receptor), and VEGF (a cytokine) expression in cultured human retinal pigment epithelium (RPE) cells were tested and serum cholesterol profiles of the clinically screened subjects were analyzed. ApoE112R (E4) distribution differed significantly between AMD patients and controls. ApoE112R allele frequency was 10.9% in the AMD group when compared with 16.5% in the younger controls and 18.8% in the clinically screened controls. The pathologically diagnosed archived AMD cases had the lowest allele frequency of 5%. No significant differences in ApoE158C (E2) distribution were observed among the groups. A meta-analysis of 8 cohorts including 4,289 subjects showed a strong association between AMD and 112R, but not 158C. In vitro studies found that recombinant ApoE suppresses CCL2 and VEGF expression in RPE cells. However, the E4 isoform showed more suppression than E3 in both cases. These results further confirm the association between ApoE112R and a decreased risk of AMD development. The underlying mechanisms may involve differential regulation of both CCL2 and VEGF by the ApoE isoforms.
doi:10.1002/em.20233
PMCID: PMC1899525  PMID: 16823865
age-related macular degeneration; apolipoprotein E, single nucleotide polymorphism; genetic susceptibility; cytokines
4.  Proof of Concept, Randomized, Placebo-Controlled Study of the Effect of Simvastatin on the Course of Age-Related Macular Degeneration 
PLoS ONE  2013;8(12):e83759.
Background
HMG Co-A reductase inhibitors are ubiquitous in our community yet their potential role in age-related macular degeneration (AMD) remains to be determined.
Methodology/Principal Findings
Objectives: To evaluate the effect of simvastatin on AMD progression and the effect modification by polymorphism in apolipoprotein E (ApoE) and complement factor H (CFH) genes. Design: A proof of concept double-masked randomized controlled study. Participants: 114 participants aged 53 to 91 years, with either bilateral intermediate AMD or unilateral non-advanced AMD (with advanced AMD in fellow eye), BCVA≥20/60 in at least one eye, and a normal lipid profile. Intervention: Simvastatin 40 mg/day or placebo, allocated 1∶1. Main outcome measures: Progression of AMD either to advanced AMD or in severity of non-advanced AMD. Results. The cumulative AMD progression rates were 70% in the placebo and 54% in the simvastatin group. Intent to treat multivariable logistic regression analysis, adjusted for age, sex, smoking and baseline AMD severity, showed a significant 2-fold decrease in the risk of progression in the simvastatin group: OR 0.43 (0.18–0.99), p = 0.047. Post-hoc analysis stratified by baseline AMD severity showed no benefit from treatment in those who had advanced AMD in the fellow eye before enrolment: OR 0.97 (0.27–3.52), p = 0.96, after adjusting for age, sex and smoking. However, there was a significant reduction in the risk of progression in the bilateral intermediate AMD group compared to placebo [adjusted OR 0.23 (0.07–0.75), p = 0.015]. The most prominent effect was observed amongst those who had the CC (Y402H) at risk genotype of the CFH gene [OR 0.08 (0.02–0.45), p = 0.004]. No evidence of harm from simvastatin intervention was detected.
Conclusion/Significance
Simvastatin may slow progression of non-advanced AMD, especially for those with the at risk CFH genotype CC (Y402H). Further exploration of the potential use of statins for AMD, with emphasis on genetic subgroups, is warranted.
Trial Registration
Australian New Zealand Clinical Trial Registry (ANZCTR) ACTRN1260500032065
doi:10.1371/journal.pone.0083759
PMCID: PMC3877099  PMID: 24391822
5.  Age-Related Macular Degeneration and the Incidence of Cardiovascular Disease: A Systematic Review and Meta-Analysis 
PLoS ONE  2014;9(3):e89600.
Importance
Research has indicated some shared pathogenic mechanisms between age-related macular degeneration (AMD) and cardiovascular disease (CVD). However, results from prior epidemiologic studies have been inconsistent as to whether AMD is predictive of future CVD risk.
Objective
To systematically review population-based cohort studies of the association between AMD and risk of total CVD and CVD subtypes, coronary heart disease (CHD) and stroke.
Data Sources
A systematic search of the PubMed and EMBASE databases and reference lists of key retrieved articles up to December 20, 2012 without language restriction.
Data Extraction
Two reviewers independently extracted data on baseline AMD status, risk estimates of CVD and methods used to assess AMD and CVD. We pooled relative risks using random or fixed effects models as appropriate.
Results
Thirteen cohort studies (8 prospective and 5 retrospective studies) with a total of 1,593,390 participants with 155,500 CVD events (92,039 stroke and 62,737 CHD) were included in this meta-analysis. Among all studies, early AMD was associated with a 15% (95% CI, 1.08–1.22) increased risk of total CVD. The relative risk was similar but not significant for late AMD (RR, 1.17; 95% CI, 0.98–1.40). In analyses restricted to the subset of prospective studies, the risk associated with early AMD did not appreciably change; however, there was a marked 66% (95% CI, 1.31–2.10) increased risk of CVD among those with late AMD.
Conclusion
Whereas the results from all cohort studies suggest that both early and late AMD are predictive of a small increase in risk of future CVD, subgroup analyses limited to prospective studies demonstrate a markedly increased risk of CVD among people with late AMD. Retrospective studies using healthcare databases may have inherent methodological limitations that obscure such association. Additional prospective studies are needed to further elucidate the associations between AMD and specific CVD outcomes.
doi:10.1371/journal.pone.0089600
PMCID: PMC3969321  PMID: 24681973
6.  Variations in Apolipoprotein E Frequency With Age in a Pooled Analysis of a Large Group of Older People 
American Journal of Epidemiology  2011;173(12):1357-1364.
Variation in the apolipoprotein E gene (APOE) has been reported to be associated with longevity in humans. The authors assessed the allelic distribution of APOE isoforms ε2, ε3, and ε4 among 10,623 participants from 15 case-control and cohort studies of age-related macular degeneration (AMD) in populations of European ancestry (study dates ranged from 1990 to 2009). The authors included only the 10,623 control subjects from these studies who were classified as having no evidence of AMD, since variation within the APOE gene has previously been associated with AMD. In an analysis stratified by study center, gender, and smoking status, there was a decreasing frequency of the APOE ε4 isoform with increasing age (χ2 for trend = 14.9 (1 df); P = 0.0001), with a concomitant increase in the ε3 isoform (χ2 for trend = 11.3 (1 df); P = 0.001). The association with age was strongest in ε4 homozygotes; the frequency of ε4 homozygosity decreased from 2.7% for participants aged 60 years or less to 0.8% for those over age 85 years, while the proportion of participants with the ε3/ε4 genotype decreased from 26.8% to 17.5% across the same age range. Gender had no significant effect on the isoform frequencies. This study provides strong support for an association of the APOE gene with human longevity.
doi:10.1093/aje/kwr015
PMCID: PMC3145394  PMID: 21498624
aged; apolipoprotein E2; apolipoprotein E3; apolipoprotein E4; apolipoproteins E; longevity; meta-analysis; multicenter study
7.  C-Reactive Protein and the Incidence of Macular Degeneration – Pooled Analysis of 5 Cohorts 
JAMA ophthalmology  2013;131(4):507-513.
Objectives
To investigate the relationship between high-sensitivity C-reactive protein (hsCRP) and future risk of age-related macular degeneration (AMD) in US men and women.
Methods
We measured hsCRP in baseline blood samples from participants in five ongoing cohort studies. Patients were initially free of AMD. We prospectively identified 647 incident cases of AMD and selected age- and sex-matched controls for each AMD case (2 controls for each case with dry AMD, or 3 controls for each case of neovascular AMD). We used conditional logistic regression models to examine the relationship between hsCRP and AMD, and pooled findings using meta-analytic techniques.
Results
After adjusting for cigarette smoking status, participants with high (> 3 mg/L) compared with low (< 1 mg/L) hsCRP levels, had cohort-specific odds ratios (OR) for incident AMD ranging from 0.94 (95% CI 0.58-1.51) in the Physicians’ Health Study to 2.59 (95% CI 0.58-11.67) in the Women’s Antioxidant and Folic Acid Cardiovascular Study. After testing for heterogeneity between studies (Q=5.61, p=0.23), we pooled findings across cohorts, and observed a significantly increased risk of incident AMD for high versus low hsCRP levels (OR=1.49, 95% CI 1.06-2.08). Risk of neovascular AMD was also increased among those with high hsCRP levels (OR=1.84, 95% CI 1.14-2.98).
Conclusion
Overall these pooled findings from 5 prospective cohorts add further evidence that elevated levels of hsCRP predict greater future risk of AMD. This information might shed light on underlying mechanisms, and could be of clinical utility in the identification of persons at high risk of AMD who may benefit from increased adherence to lifestyle recommendations, eye examination schedules, and therapeutic protocols.
doi:10.1001/jamaophthalmol.2013.2303
PMCID: PMC3625501  PMID: 23392454
8.  Association between Polymorphisms of Complement Pathway Genes and Age-Related Macular Degeneration in a Chinese Population 
Purpose.
We assessed the association between complement pathway genes and age-related macular degeneration (AMD) in a Chinese population.
Methods.
In a case-control study, 165 AMD patients and 216 unrelated controls were recruited from two hospitals in central China. We selected and genotyped six single nucleotide polymorphisms (SNPs) of four complement pathway genes, including rs800292 and rs1410996 of complement H (CFH), rs9332739 of complement 2 (C2), rs4151667 of complement factor B (CFB), and rs2241394 and rs2230199 of complement 3 (C3). The associations between SNPs and AMD, adjusted by age and sex, were assessed by using logistic regression models and haplotype association analysis.
Results.
In our study, two SNPs of CFH and their haplotypes were associated significantly with AMD, and the adjusted odd ratios (ORs) were 2.45 (95% confidence interval [CI] 1.25–4.79) for rs800292 (genotype GG versus AA), 2.49 (95% CI 1.24–5.00) for rs1410996 (genotype TT versus CC), and 4.45 (95% CI 2.32–8.55) for haplotype block of rs800292–rs1410996 (haplotype G–C versus A–C), respectively. The haplotype of C2/CFB also was associated significantly with AMD, and the adjusted OR was 8.86 (95% CI 1.88–41.69) for the haplotype block of rs9332739–rs4151667 (haplotype G–A versus G–T), though no relationship was found in genotype association analysis of the two SNPs of C2/CFB. With the sample size of our study, no relationship was found for AMD and the two SNPs of C3.
Conclusions.
Gene variants in CFH and C2/CFB contribute to AMD in the Chinese population.
The association between age-related macular degeneration (AMD) and six single-nucleotide polymorphisms (SNPs) at 4 complement pathway genes, including rs800292 (CFH), rs1410996 (CFH), rs4151667 (CFB), rs9332739 (C2), rs2241394 (C3), and rs2230199 (C3), were studied in a Chinese population.
doi:10.1167/iovs.12-10453
PMCID: PMC3544419  PMID: 23233260
9.  Multilocus analysis of age-related macular degeneration 
Age-related macular degeneration (AMD) is a late onset vision disorder. Recent studies demonstrate that alterations in complement cascade genes are associated with AMD. Of the three identified complement loci, variants in complement factor H (CFH) have the highest impact as does an independent locus at 10q26. Our matched case–control study using the Age-Related Eye Disease Study (AREDS) cohort confirms and extends the associations in these loci. Subjects were genotyped for single nucleotide polymorphisms (SNPs) from CFH, complement component 2 (C2), complement component 3 (C3), complement factor B (CFB), age-related maculopathy susceptibility (ARMS2), HtrA serine peptidase 1 (HTRA1), and apolipoprotein E (APOE). Individual SNPs, and haplotypes showed risk trends consistent with those seen in other population studies for CFH, C3, C2, and CFB. SNP rs10490924 on chromosome 10 in exon 1 of the ARMS2 gene showed a highly significant association with an odds ratio (OR) of 3.2 (95% CI 2.4–4.2) for the risk allele and rs11200638 located in the proximal promoter region of HTRA1 showed a higher significant association with an OR of 3.4 (95% CI 2.5–4.6) with our AMD cases. We found that APOE haplotypes were not significantly associated with disease status. Adjustments for other risk factors did not significantly alter the observed associations. This study validates the complement pathway’s involvement in AMD and suggests that allelic variants in complement genes have a direct role in disease. These results also support previous findings that variants in the region of 10q26 exert an independent risk for AMD.
doi:10.1038/ejhg.2009.23
PMCID: PMC2729805  PMID: 19259132
age-related macular degeneration; complement; ARMS2; HTRA1
10.  Multilocus analysis of age-related macular degeneration 
European Journal of Human Genetics  2009;17(9):1190-1199.
Age-related macular degeneration (AMD) is a late onset vision disorder. Recent studies demonstrate that alterations in complement cascade genes are associated with AMD. Of the three identified complement loci, variants in complement factor H (CFH) have the highest impact as does an independent locus at 10q26. Our matched case–control study using the Age-Related Eye Disease Study (AREDS) cohort confirms and extends the associations in these loci. Subjects were genotyped for single nucleotide polymorphisms (SNPs) from CFH, complement component 2 (C2), complement component 3 (C3), complement factor B (CFB), age-related maculopathy susceptibility (ARMS2), HtrA serine peptidase 1 (HTRA1), and apolipoprotein E (APOE). Individual SNPs, and haplotypes showed risk trends consistent with those seen in other population studies for CFH, C3, C2, and CFB. SNP rs10490924 on chromosome 10 in exon 1 of the ARMS2 gene showed a highly significant association with an odds ratio (OR) of 3.2 (95% CI 2.4–4.2) for the risk allele and rs11200638 located in the proximal promoter region of HTRA1 showed a higher significant association with an OR of 3.4 (95% CI 2.5–4.6) with our AMD cases. We found that APOE haplotypes were not significantly associated with disease status. Adjustments for other risk factors did not significantly alter the observed associations. This study validates the complement pathway's involvement in AMD and suggests that allelic variants in complement genes have a direct role in disease. These results also support previous findings that variants in the region of 10q26 exert an independent risk for AMD.
doi:10.1038/ejhg.2009.23
PMCID: PMC2729805  PMID: 19259132
age-related macular degeneration; complement; ARMS2; HTRA1
11.  Lack of association between the c.544G>A polymorphism of the heme oxygenase-2 gene and age-related macular degeneration 
Summary
Background
Age-related macular degeneration (AMD) is a primary cause of blindness among the elderly in developed countries. The nature of AMD is complex and includes both environmental and hereditary factors. Oxidative stress is thought to be essential in AMD pathogenesis. Iron is suggested to be implicated in the pathogenesis of AMD through the catalysis of the production of reactive oxygen species, which can damage the retina. Heme oxygenase-2 is capable of degradation of heme producing free iron ions, thus, diversity in heme oxygenase-2 gene may contribute to AMD. In the present work we analyzed the association between the c.544G>A polymorphism of the heme oxygenase-2 gene (HMOX2) (rs1051308) and AMD.
Material/Methods
This study enrolled 276 AMD patients and 105 sex- and age-matched controls. Genotyping of the polymorphism was performed with restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) on DNA isolated from peripheral blood.
Results
We did not find any association between the genotypes of the c.544G>A polymorphism and the occurrence of AMD. This lack of association was independent of potential AMD risk factors: tobacco smoking, sex and age. Moreover, we did not find any association between AMD and smoking in our study population.
Conclusions
The results suggest that the c.544G>A polymorphism of the heme oxygenase-2 gene is not associated with AMD in this Polish subpopulation.
doi:10.12659/MSM.881906
PMCID: PMC3539623  PMID: 21804464
heme oxygenase-2; HMOX2 gene; age-related macular degeneration (AMD); genetic polymorphism; iron metabolism
12.  Association of Variants in the LIPC and ABCA1 Genes with Intermediate and Large Drusen and Advanced Age-Related Macular Degeneration 
HDL pathway genes LIPC and ABCA1 are associated with intermediate drusen, large drusen, and advanced AMD independent of age, sex, education, smoking, body mass index, antioxidant treatment, and other known genetic variants.
Purpose.
Intermediate and large drusen usually precede advanced age-related macular degeneration (AMD). There is little information about which genes influence drusen accumulation. Discovery of genetic variants associated with drusen may lead to prevention and treatments of AMD in its early stages.
Methods.
A total of 3066 subjects were evaluated on the basis of ocular examinations and fundus photography and categorized as control (n = 221), intermediate drusen (n = 814), large drusen (n = 949), or advanced AMD (n = 1082). SNPs in the previously identified CFH, C2, C3, CFB, CFI, APOE, and ARMS2/HTRA1 genes/regions and the novel genes LIPC, CETP, and ABCA1 in the high-density lipoprotein (HDL) cholesterol pathway were genotyped. Associations between stage of AMD and SNPs were assessed using logistic regression.
Results.
Controlling for age, sex, education, smoking, body mass index, and antioxidant treatment, the number of minor (T) alleles of the genes LIPC and ABCA1 were significantly associated with a reduced risk of intermediate drusen (LIPC [P trend = 0.045], ABCA1 [P = 4.4 × 10−3]), large drusen (LIPC [P = 0.041], ABCA1 [P = 7.7 × 10−4]), and advanced AMD (LIPC [P = 1.8 × 10−3], ABCA1 [P = 3 × 10−4]). After further adjustment for known genetic factors, the protective effect of the TT genotype was significant for intermediate drusen (LIPC [odds ratio (OR), 0.56; 95% confidence interval (CI), 0.33–0.94], ABCA1 [OR, 0.48; 95% CI, 0.27–0.85]), large drusen (LIPC [OR, 0.58; 95% CI, 0.34–0.98)], ABCA1 [OR, 0.41; 95% CI, 0.23–0.74)]), and advanced AMD (LIPC [OR, 0.39; 95% CI, 0.21–0.74)], ABCA1 [OR, 0.35; 95% CI, 0.17–0.71)]). CFH, C3, C2, and ARMS2/HTRA1 were associated with large drusen and advanced AMD.
Conclusions.
LIPC and ABCA1 are related to intermediate and large drusen, as well as advanced AMD. CFH, C3, C2, and ARMS2/HTRA1 are associated with large drusen and advanced AMD. Genes may have varying effects on different stages of AMD.
doi:10.1167/iovs.10-7070
PMCID: PMC3175969  PMID: 21447678
13.  Common variation in the SERPING1 gene is not associated with age-related macular degeneration in two independent groups of subjects 
Molecular Vision  2009;15:200-207.
Purpose
Common genetic variation in the complement component 1 inhibitor gene (SERPING1) was recently reported to increase the risk of developing age-related macular degeneration (AMD). This study was performed to replicate the association between SERPING1 and AMD.
Methods
Seven single nucleotide polymorphisms (SNPs) tagging common haplotypes across SERPING1 were genotyped on 786 (The Mayo Clinic) subjects and the association with AMD studied using single SNP and haplotype association analyses. The SNP in intron 6 (rs2511989) previously reported to increase the risk of AMD was studied in an additional 1,541 subjects from the Age-Related Eye Disease Study (AREDS). Association with specific subtypes of AMD and interaction with four other loci: complement factor H (CFH), age-related maculopathy susceptibility 2 (ARMS2/LOC387715), High Temperature Requirement Factor A1 (HTRA1), complement factor B/complement component 2 (CFB/C2), and complement component 3 (C3) involved in AMD was explored.
Results
The seven tag-SNPs were not associated with AMD in the Mayo subjects (p=0.13–0.70) and rs2511989 was also not associated with AMD in the Mayo or AREDS subjects (p=0.44–0.45). Evaluation of haplotypes across SERPING1 did not reveal association with AMD (p=0.14–0.97). SNPs were not associated with AMD subtypes (early, geographic atrophy, or exudation). No interaction with other AMD risk variants was observed.
Conclusions
We were unable to replicate the reported association between SERPING1 and AMD in two independent groups of subjects.
PMCID: PMC2629736  PMID: 19169411
14.  A Human ApoB100 Transgenic Mouse expresses human ApoB100 in the RPE and develops features of early AMD 
Experimental eye research  2009;88(6):1115-1123.
ApoB100 lipoprotein particles have been found to accumulate in Bruch membrane prior to the development of Age-related macular degeneration (AMD). This work was performed to determine whether mice that overexpress apoB100 in the RPE-choroid and liver develop landmarks of early AMD over time. Mice transgenic for a human genomic fragment encoding the full length human ApoB (“ApoB100” mice) and litter-mate control mice were given a normal chow or high fat diet for 12 months. Mice were evaluated for human apoB mRNA expression in the RPE/choroid and liver by RT-qPCR. Phenotypic changes associated with early AMD were evaluated by ultrastructural analysis using transmission electron microscopy. Changes were semi-quantified using linear regression analysis. Both the RPE/choroid and liver of ApoB100 mice expressed both human and mouse ApoB mRNA. Transmission electron microscopy showed ultrastructural changes consistent with early human AMD including loss of basal infoldings and accumulation of cytoplasmic vacuoles in the RPE, and basal laminar deposits containing long spacing collagen and heterogeneous debris in Bruch membrane of ApoB100 mice. In ApoB100 mice given a high fat diet, basal linear-like deposits were identified in 12 month old mice. Linear regression analysis showed that the genotype (human ApoB transgene) was a stronger influencing factor than high fat diet in producing AMD-like lesions used in this study. Human ApoB100 transgenic mice overexpress apoB in RPE and, with time, develop validated phenotypic changes that are seen in early human AMD. The phenotypic changes were aggravated by feeding a high-fat diet. The ApoB100 mouse model could be valuable in determining the role of apoB containing lipoproteins in triggering the onset of early AMD.
doi:10.1016/j.exer.2009.01.017
PMCID: PMC2729121  PMID: 19450445
Age-related macular degeneration; basal laminar deposit; basal linear deposit; apolipoprotein B; lipoproteins; retinal pigmented epithelium
15.  Chlamydia pneumoniae infection, complement factor H variants and age-related macular degeneration 
Background/aims
Impaired inhibition of the alternative complement pathway by complement factor H (CFH) is linked to age-related macular degeneration (AMD) based on the strong association between CFH variant and AMD. Chlamydia pneumoniae (C pneumoniae) infection can trigger the alternative pathway, but the evidence for an association between C pneumoniae and AMD is contradictory. This study investigated whether C pneumoniae infection is associated with AMD and whether the presence of C pneumonia modulates AMD risk conferred by CFH variants.
Methods
Genomic DNA extracted from peripheral blood of 148 advanced AMD patients and 162 controls was subjected to Taqman and PCR-RFLP for the CFH polymorphism and PCR for the C pneumoniae gene. Genomic DNA was also examined from microdissected macular cells from 59 AMD and 16 age-matched non-AMD archived slides. χ2 testing was performed for case-control analysis.
Results
C pneumoniae infection was associated with increased risk of AMD (OR = 2.17, p<0.017). A CFH variant was also linked to increased risk of AMD (OR = 1.98, p<0.0001). However, no relationship was found between risk-conferring CFH variant and C pneumoniae (OR = 1.81, p = 0.08).
Conclusion
There is a possible association between AMD and C pneumoniae infection, although CFH may not be directly involved in the pathogenesis of C pneumoniae infection-mediated AMD.
doi:10.1136/bjo.2008.145383
PMCID: PMC2746818  PMID: 18996904
16.  The Y402H Variant in the Complement Factor H Gene Affects Incidence and Progression of Age-Related Macular Degeneration: Results from Multi-State Models Applied to the Beaver Dam Eye Study 
Archives of ophthalmology  2012;130(9):1169-1176.
Objective
To investigate the impact of age, sex and the Y402H variant in the complement factor H (CFH) gene on incidence, progression and regression of age-related macular degeneration (AMD) and the impact of these factors and AMD on mortality using multi-state models (MSMs).
Methods
Analyses included 4,379 persons aged 43 to 86 years at the time of initial examination. AMD status on a 5-level severity scale was graded from retinal photographs taken at up to 5 study visits between 1988 and 2010. MSMs in continuous time were used to model the effects of age, sex and CFH genotype on incidence, progression and regression of AMD and mortality.
Results
CFH Y402H genotype CC was associated, relative to genotype TT (reported as hazard ratio, 95% confidence interval), with increased incidence of AMD (no to minimally severe early AMD: 1.98, 1.57–2.49), progression of AMD (minimally severe early to moderately severe early AMD: 1.73, 1.29–2.33; moderately severe early to severe early AMD: 1.30, 0.86–1.94; and severe early to late AMD: 1.72, 1.01–2.91), but not with regression of AMD or mortality. Late AMD was associated with increased mortality (1.37, 1.15–1.62) relative to no AMD, but earlier stages of AMD were not.
Conclusions
Using MSMs, we show that the Y402H risk variant elevates lifetime incidence of early AMD and progression of early to late AMD, and that late AMD elevates mortality risk.
doi:10.1001/archophthalmol.2012.693
PMCID: PMC3495559  PMID: 22965593
age-related macular degeneration; CFH; epidemiology
17.  HTRA1 Variants in Exudative Age-Related Macular Degeneration and Interactions with Smoking and CFH 
Purpose
Mapping the genes for age-related macular degeneration (AMD) had not been successful until recent genome-wide association studies revealed Tyr402His in CFH and rs11200638 in HTRA1 as AMD-related genetic variants. This study was conducted to identify other critical factors in HTRA1 that are associated with exudative AMD.
Methods
The promoter, splice regions, and coding exons of HTRA1 were sequenced in 163 patients with exudative AMD and 183 sex- and age-matched control subjects. Also documented were the CFH genotype and smoking status.
Results
Four significant SNPs were found in the promoter and the first exon of HTRA1: rs11200638 (–625G>A), rs2672598 (–487T>C), rs1049331 (102C>T, Ala34Ala), and rs2293870 (108G>T, Gly36Gly) with respective P = 1.7 × 10−14, 3.0 × 10− 10, 3.7 × 10−12, and 3.7 × 10−12. Among them, rs11200638 is the most significant associated SNP with a high odds ratio (OR) of 7.6 (95% CI: 3.94–14.51). One risk haplotype block across the promoter and exon 1, ACCTT, significantly predisposes to AMD (P = 6.68 × 10−14). In both models, significant independent additive effects were identified with smoking and rs800292 (184G>A, Val62Ile) of CFH. Smoking and rs11200638 (HTRA1) combined caused a 15.7-fold increased risk, whereas combined rs800292 and rs11200638 caused a 23.3-fold increased risk. An extremely high population attributable risk (PAR) of 78% was also found.
Conclusions
A high impact of the additive effect of CFH and HTRA1 in the development of exudative AMD was shown. The HTRA1-smoking additive effect found in this study further suggests the importance of this environmental risk factor in AMD.
doi:10.1167/iovs.07-1520
PMCID: PMC3215269  PMID: 18316707
18.  A case control study of age related macular degeneration and use of statins 
The British Journal of Ophthalmology  2005;89(9):1171-1175.
Aims: Age related macular degeneration (AMD) is the leading cause of blindness in industrialised countries. Previous studies have suggested that statins may have a protective effect against the disease; however, existing studies have had limited power to reliably detect or exclude an effect and have produced conflicting results. The authors assessed the risk of AMD associated with the use of statins.
Methods: Population based case control study using the United Kingdom General Practice Research Database. 18 007 people with diagnosed AMD were compared with 86 169 controls matched on age, sex, and general practice. The primary outcome was the odds ratio for the association between exposure to statins and AMD.
Results: The crude odds ratio for the association between any recorded exposure to statins and AMD was 1.32 (95% CI 1.17 to 1.48), but this reduced to 0.93 (95% CI 0.81 to 1.07, p = 0.33) after adjustment for consultation rate, smoking, alcohol intake, body mass index, atherosclerotic disease, hyperlipidaemia, heart failure, diabetes mellitus, hypertension, use of other cardiovascular drugs, and use of fibrates. There was no evidence that the risk varied by dose of statin, duration of use, or that the risk varied for individual statins.
Conclusion: In the short and medium term statin use is not associated with a decreased risk of AMD. Whether subgroups of patients with specific forms of AMD (particularly choroidal neovascularisation) benefit from statin therapy remains a possibility.
doi:10.1136/bjo.2004.064477
PMCID: PMC1772815  PMID: 16113375
age related macular degeneration; statins; case control
19.  Does smoking influence the type of age related macular degeneration causing visual impairment? 
Aims
To assess the influence of smoking on the type of age related macular degeneration (AMD) lesion causing visual impairment in a large cohort of patients with AMD at a tertiary referral UK centre.
Methods
Prospective, observational, cross sectional study to analyse smoking data on 711 subjects, of western European origin, in relation to the type of AMD lesion present. Colour fundus photographs were graded according to a modified version of the international classification. Multiple logistic regression analysis was performed, adjusting for age and sex using the statistical package SPSS ver 9.0 for Windows. χ2 tests were also used to assess pack year and ex‐smoker data.
Results
578 subjects were graded with neovascular AMD and 133 with non‐neovascular AMD. There was no statistically significant association found between smoking status or increasing number of pack years and type of AMD lesion. The odds of “current smokers” compared to “non‐smokers” developing neovascular rather than non‐neovascular AMD when adjusted for age and sex was 1.88 (95% CI: 0.91 to 3.89; p = 0.09).
Conclusions
Smoking is known to be a risk factor for AMD and this study suggests that smokers are at no more risk of developing neovascular than atrophic lesions.
doi:10.1136/bjo.2005.086355
PMCID: PMC1860217  PMID: 16597668
age related macular degeneration; smoking; neovascular
20.  Aspirin Use and Risk of Age-Related Macular Degeneration: A Meta-Analysis 
PLoS ONE  2013;8(3):e58821.
Background
Age-related macular degeneration (AMD) is the main cause of blindness and the curative options are limited. The objective of this meta-analysis was to determine the association between aspirin use and risk of AMD.
Methods
A comprehensive literature search was performed in PubMed, Embase, Web of Science, and reference lists. A meta-analysis was performed by STATA software.
Results
Ten studies involving 171729 individuals examining the association between aspirin use and risk of AMD were included. Among the included studies, 2 were randomized-controlled trials (RCTs), 4 were case-control studies and 4 were cohort studies. The relative risks (RRs) were pooled using a random-effects model. Relative risks with 95% confidence intervals (CIs) of aspirin use as a risk for AMD. The pooled RR of 10 included studies between the use of aspirin and risk of AMD was 1.09 (95% CI, 0.96–1.24). The same result was detected in early and late stage AMD subgroup analysis. In the subgroup analyses, the pooled RR of RCTs, case-control studies and cohort studies were 0.81 (95% CI, 0.64–1.02), 1.02 (95% CI, 0.92–1.14) and 1.08 (95% CI, 0.91–1.28), respectively.
Conclusions
The use of aspirin was not associated with the risk of AMD.
doi:10.1371/journal.pone.0058821
PMCID: PMC3597550  PMID: 23516561
21.  Effect of the Gas6 c.834+7G>A Polymorphism and the Interaction of Known Risk Factors on AMD Pathogenesis in Hungarian Patients 
PLoS ONE  2012;7(11):e50181.
Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly in the developed world. Numerous genetic factors contribute to the development of the multifactorial disease. We performed a case-control study to assess the risk conferred by known and candidate genetic polymorphisms on the development of AMD. We searched for genetic interactions and for differences in dry and wet AMD etiology. We enrolled 213 patients with exudative, 67 patients with dry AMD and 106 age and ethnically matched controls. Altogether 12 polymorphisms in Apolipoprotein E, complement factor H, complement factor I, complement component 3, blood coagulation factor XIII, HTRA1, LOC387715, Gas6 and MerTK genes were tested. No association was found between either the exudative or the dry form and the polymorphisms in the Apolipoprotein E, complement factor I, FXIII and MerTK genes. Gas6 c.834+7G>A polymorphism was found to be significantly protective irrespective of other genotypes, reducing the odds of wet type AMD by a half (OR = 0.50, 95%CI: 0.26–0.97, p = 0.04). Multiple regression models revealed an interesting genetic interaction in the dry AMD subgroup. In the absence of C3 risk allele, mutant genotypes of both CFH and HTRA1 behaved as strongly significant risk factors (OR = 7.96, 95%CI: 2.39 = 26.50, p = 0.0007, and OR = 36.02, 95%CI: 3.30–393.02, p = 0.0033, respectively), but reduced to neutrality otherwise. The risk allele of C3 was observed to carry a significant risk in the simultaneous absence of homozygous CFH and HTRA1 polymorphisms only, in which case it was associated with a near-five-fold relative increase in the odds of dry type AMD (OR = 4.93, 95%CI: 1.98–12.25, p = 0.0006). Our results suggest a protective role of Gas6 c.834+7G>A polymorphism in exudative AMD development. In addition, novel genetic interactions were revealed between CFH, HTRA1 and C3 polymorphisms that might contribute to the pathogenesis of dry AMD.
doi:10.1371/journal.pone.0050181
PMCID: PMC3510257  PMID: 23209669
22.  Insights into the Genetic Architecture of Early Stage Age-Related Macular Degeneration: A Genome-Wide Association Study Meta-Analysis 
PLoS ONE  2013;8(1):e53830.
Genetic factors explain a majority of risk variance for age-related macular degeneration (AMD). While genome-wide association studies (GWAS) for late AMD implicate genes in complement, inflammatory and lipid pathways, the genetic architecture of early AMD has been relatively under studied. We conducted a GWAS meta-analysis of early AMD, including 4,089 individuals with prevalent signs of early AMD (soft drusen and/or retinal pigment epithelial changes) and 20,453 individuals without these signs. For various published late AMD risk loci, we also compared effect sizes between early and late AMD using an additional 484 individuals with prevalent late AMD. GWAS meta-analysis confirmed previously reported association of variants at the complement factor H (CFH) (peak P = 1.5×10−31) and age-related maculopathy susceptibility 2 (ARMS2) (P = 4.3×10−24) loci, and suggested Apolipoprotein E (ApoE) polymorphisms (rs2075650; P = 1.1×10−6) associated with early AMD. Other possible loci that did not reach GWAS significance included variants in the zinc finger protein gene GLI3 (rs2049622; P = 8.9×10−6) and upstream of GLI2 (rs6721654; P = 6.5×10−6), encoding retinal Sonic hedgehog signalling regulators, and in the tyrosinase (TYR) gene (rs621313; P = 3.5×10−6), involved in melanin biosynthesis. For a range of published, late AMD risk loci, estimated effect sizes were significantly lower for early than late AMD. This study confirms the involvement of multiple established AMD risk variants in early AMD, but suggests weaker genetic effects on the risk of early AMD relative to late AMD. Several biological processes were suggested to be potentially specific for early AMD, including pathways regulating RPE cell melanin content and signalling pathways potentially involved in retinal regeneration, generating hypotheses for further investigation.
doi:10.1371/journal.pone.0053830
PMCID: PMC3543264  PMID: 23326517
23.  Instability in X chromosome inactivation patterns in AMD: a new risk factor? 
Years ago, it was thought that a genetic component was the fundamental cause of a number retinopathy diseases including age related macular degeneration (AMD). Since then, information has emerged about novel genes that contribute to various forms of AMD and other retinopathies that have been eluding researchers for years. In the genetic sense, only the APOE 2 and 4 genes have been found to be a risk factor for sporadic AMD. But, a recent Genome wide association study (GWAS) revealed that an alteration of five SNIPs on the X chromosome in a gene named DIAPH2 may be a susceptibility gene for AMD. Furthermore, the gene DIAPH2 showed to have a polygenic pleiotropy for premature ovarian failure (POF) and AMD in a cohort of women. POF is highly associated with X chromosome skewing, an epigenetic alteration of the inactivation process of the X chromosome. These findings suggest a hypothesis that an epigenetic alteration on the inactivation centres of the X chromosome (or skewing) relates not only to aging, but might be a novel property that affects women with AMD more often than men.
PMCID: PMC3939760  PMID: 24600647
X Chromosome; AMD; DIAPH2 Gene; X Chromosome Skewing
24.  Smoking and age related macular degeneration: the number of pack years of cigarette smoking is a major determinant of risk for both geographic atrophy and choroidal neovascularisation 
Background/aims
There is evidence that smoking is a risk factor for age related macular degeneration (AMD). However, not all studies have demonstrated this association and several key questions about the role of smoking in AMD have still to be determined. The aim of this study was to further investigate this relation for both choroidal neovascularisation (CNV) and geographic atrophy (GA).
Methods
To investigate the relation between smoking and the risk of developing age related macular degeneration (AMD) in white people, 435 cases with end stage AMD were compared with 280 controls. All subjects had graded stereoscopic colour fundus photography and AMD was defined as the presence of GA or CNV. Smoking history was assessed using multiple parameters in a detailed questionnaire.
Results
Comparison of current and former smokers with non‐smokers was consistent with smoking being a risk factor for AMD but did not reach statistical significance. There was a strong association between AMD and pack years of cigarette smoking (p = 0.002), the odds ratio increasing with the amount smoked; for subjects with more than 40 pack years of smoking the odds ratio was 2.75 (95% CI 1.22 to 6.20) compared with non‐smokers. Both types of AMD showed a similar relation; smoking more than 40 pack years of cigarettes was associated with an odds ratio of 3.43 (95% CI 1.28 to 9.20) for GA and 2.49 (95% CI 1.06 to 5.82) for CNV. Stopping smoking was associated with reduced odds of AMD and the risk in those who had not smoked for over 20 years was comparable to non‐smokers. The risk profile was similar for males and females. Passive smoking exposure was associated with an increased risk of AMD (OR 1.87; 95% CI 1.03 to 3.40) in non‐smokers.
Conclusions
The authors have demonstrated a strong association between the risk of both GA and CNV and pack years of cigarette smoking. This provides support for a causal relation between smoking and AMD. They also show an increased risk for AMD in non‐smokers exposed to passive smoking. Stopping smoking appears to reduce the risk of developing AMD.
doi:10.1136/bjo.2005.073643
PMCID: PMC1856879  PMID: 16361672
age related macular degeneration; smoking; case control
25.  Cognitive Impairment in the Age-Related Eye Disease Study 
Archives of ophthalmology  2006;124(4):537-543.
Objective
To investigate potential associations between cognitive function and/or impairment and age-related macular degeneration (AMD) and visual impairment in the Age-Related Eye Disease Study (AREDS).
Methods
The AREDS is an 11-center natural history study of AMD and age-related cataract. The AREDS Cognitive Function Battery was administered to 2946 participants. The battery consists of 6 neuropsychological tests measuring performance in several cognitive domains. The Dunnett multiple comparison test was used to identify differences by AMD and visual acuity severity. The relationship with cognitive impairment was also assessed using logistic regression.
Results
Mean scores of instruments in the AREDS Cognitive Function Battery declined with increased macular abnormalities and reduced visual acuity. After adjustment for age, sex, race, education, smoking status, diabetes mellitus, hypertension, and depression, increased macular abnormalities (trend P value <.05) reduced mean cognitive function scores as measured by the Modified Mini-Mental State Examination and the Wechsler Logical Memory Scale. Reduced vision was found to be associated with reduced mean cognitive function scores as measured by the Modified Mini-Mental State Examination and letter and verbal fluency tasks. Persons with vision worse than 20/40 OU were more likely to be cognitively impaired (Modified Mini-Mental State Examination score <80) (odds ratio, 2.88 [95% confidence interval, 1.75–4.76]) compared with persons with visual acuity of 20/40 or better OU.
Conclusion
These data suggest a possible association of advanced AMD and visual acuity with cognitive impairment in older persons.
doi:10.1001/archopht.124.4.537
PMCID: PMC1472655  PMID: 16606880

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