The Y402H variant of complement factor H is associated with age-related macular degeneration but not with diabetic retinal disease in the Go-DARTS study

CFB/C2 gene polymorphisms and risk of age-related macular degeneration: a systematic review and meta-analysis

PURPOSE

To investigate whether the polymorphisms of CFB/C2 gene are associated with age-related macular degeneration (AMD), and to evaluate the magnitude of gene effect.

METHODS

We performed a meta-analysis of the association between four SNPs in CFB/C2 gene (rs9332739, rs547154, rs4151667, and rs641153) and risk of AMD using data from 15 case-control studies involving 8905 subjects. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed- and random-effects models. The Q and I(2) statistics were used to evaluate between-study heterogeneity. Harbord's modified test was used to detect small study effects. Sensitivity analysis, cumulative meta-analysis, and meta-regression were also performed.

RESULTS

For rs9332739, rs547154, rs4151667, and rs641153, the pooled ORs in a dominant genetic model were 0.474 (fixed effects, P < 0.001, 95% CI 0.378-0.596), 0.399 (random effects, 95% CI 0.289-0.551, P < 0.001), 0.496 (fixed effects, 95% CI 0.390-0.632, P < 0.001), and 0.557 (random effects, P = 0.008, 95% CI 0.362-0.856), respectively. These results suggested that variant alleles of all the four SNPs has significant protective effect against AMD. Contour-enhanced funnel plots and Harbord's test showed moderate small study effects for rs9332739 and rs4151667. Heterogeneity were found for rs547154 and rs641153, subgroup analysis suggested that ethnicity was the main source for heterogeneity. Stratification by ethnicity indicated stronger protective effects of rare alleles in Caucasians. Genotype distribution analysis also suggested that frequencies of rare homozygous genotype were higher in Caucasian group.

CONCLUSIONS

Our meta-analysis indicated strong protective effects of the variant alleles of four SNPs in CFB/C2 gene (rs9332739, rs547154, rs4151667, and rs641153) against AMD. The disease risk descended to nearly one half for individuals carrying at least one copy of the rare alleles. The protective effects seemed to be stronger in Caucasians, of which the genotype frequencies were also higher.

Candidate gene association study for diabetic retinopathy in persons with type 2 diabetes: the Candidate gene Association Resource (CARe)

PURPOSE

To investigate whether variants in cardiovascular candidate genes, some of which have been previously associated with type 2 diabetes (T2D), diabetic retinopathy (DR), and diabetic nephropathy (DN), are associated with DR in the Candidate gene Association Resource (CARe).

METHODS

Persons with T2D who were enrolled in the study (n = 2691) had fundus photography and genotyping of single nucleotide polymorphisms (SNPs) in 2000 candidate genes. Two case definitions were investigated: Early Treatment Diabetic Retinopathy Study (ETDRS) grades ≥ 14 and ≥ 30. The χ² analyses for each CARe cohort were combined by Cochran-Mantel-Haenszel (CMH) pooling of odds ratios (ORs) and corrected for multiple hypothesis testing. Logistic regression was performed with adjustment for other DR risk factors. Results from replication in independent cohorts were analyzed with CMH meta-analysis methods.

RESULTS

Among 39 genes previously associated with DR, DN, or T2D, three SNPs in P-selectin (SELP) were associated with DR. The strongest association was to rs6128 (OR = 0.43, P = 0.0001, after Bonferroni correction). These associations remained significant after adjustment for DR risk factors. Among other genes examined, several variants were associated with DR with significant P values, including rs6856425 tagging α-l-iduronidase (IDUA) (P = 2.1 × 10(-5), after Bonferroni correction). However, replication in independent cohorts did not reveal study-wide significant effects. The P values after replication were 0.55 and 0.10 for rs6128 and rs6856425, respectively.

CONCLUSIONS

Genes associated with DN, T2D, and vascular diseases do not appear to be consistently associated with DR. A few genetic variants associated with DR, particularly those in SELP and near IDUA, should be investigated in additional DR cohorts.