Purpose

To compare plasma levels of oxidative stress biomarkers in patients with age-related macular degeneration (AMD) and controls and to evaluate a potential relationship between biochemical markers of oxidative stress and AMD susceptibility genotypes.

Design

Prospective case-control study

Methods

Plasma levels of oxidative stress biomarkers were determined in 77 AMD patients and 75 controls recruited from a clinical practice. Cysteine (Cys), cystine (CySS), glutathione (GSH), isoprostane (IsoP), and isofuran (IsoF) were measured, and participants were genotyped for polymorphisms in the complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) genes.

Results

CySS was elevated in cases compared to controls (p = 0.013). After adjustment for age, gender, and smoking, this association was not significant. In all participants, CySS levels were associated with the CFH polymorphism rs3753394 (p = 0.028) as well as an eight-allele CFH haplotype (p = 0.029) after correction for age, gender, and smoking. None of the other plasma markers was related to AMD status in our cohort.

Conclusions

Our investigation of the gene/environment interaction involved in AMD revealed a relationship between a plasma biomarker of oxidative stress (CySS) and CFH genotype. These data suggest a potential association between inflammatory regulators and redox status in AMD pathogenesis.

Aims

To determine whether complement factor H (CFH) genotypes have a pharmacogenetic effect on the treatment of exudative age-related macular degeneration (AMD) with ranibizumab.

Methods

A retrospective study of 156 patients with exudative AMD treated with intravitreal ranibizumab monotherapy was conducted. AMD phenotypes were characterized by clinical examination, visual acuity, fundus photography, fluorescein angiography, and injection timing. Patients received intravitreal ranibizumab injections as part of routine ophthalmologic care and were followed for a minimum of nine months. Each patient was genotyped for the single nucleotide polymorphism rs1061170 (Y402H) in the CFH gene.

Results

Baseline lesion size and angiographic type, as well as mean visual acuities at baseline, 6 months, and 9 months were similar among the three CFH genotypes. Over 9 months, patients with both risk alleles received approximately one more injection (p = 0.09). In a recurrent event analysis, patients homozygous for the CFH Y402H risk allele had a 37% significantly higher risk of requiring additional ranibizumab injections (p = 0.04)

Conclusions

In our cohort, response to treatment of AMD with ranibizumab differed according to CFH genotype, suggesting that determining patients' CFH genotype may be helpful in the future in tailoring treatment for exudative AMD with intravitreal ranibizumab.

Pharmacogenetics seeks to explain interpatient variability in response to medications by investigating genotype-phenotype correlations. There is a small but growing body of data regarding the pharmacogenetics of both nonexudative and exudative age-related macular degeneration. Most reported data concern polymorphisms in the complement factor H and age-related maculopathy susceptibility 2 genes. At this time, the data are not consistent and no definite conclusions may be drawn. As clinical trials data continue to accumulate, these relationships may become more apparent.

Despite significant progress in the identification of genetic loci for age-related macular degeneration (AMD), not all of the heritability has been explained. To identify variants which contribute to the remaining genetic susceptibility, we performed the largest meta-analysis of genome-wide association studies to date for advanced AMD. We imputed 6 036 699 single-nucleotide polymorphisms with the 1000 Genomes Project reference genotypes on 2594 cases and 4134 controls with follow-up replication of top signals in 5640 cases and 52 174 controls. We identified two new common susceptibility alleles, rs1999930 on 6q21-q22.3 near FRK/COL10A1 [odds ratio (OR) 0.87; P = 1.1 × 10−8] and rs4711751 on 6p12 near VEGFA (OR 1.15; P = 8.7 × 10−9). In addition to the two novel loci, 10 previously reported loci in ARMS2/HTRA1 (rs10490924), CFH (rs1061170, and rs1410996), CFB (rs641153), C3 (rs2230199), C2 (rs9332739), CFI (rs10033900), LIPC (rs10468017), TIMP3 (rs9621532) and CETP (rs3764261) were confirmed with genome-wide significant signals in this large study. Loci in the recently reported genes ABCA1 and COL8A1 were also detected with suggestive evidence of association with advanced AMD. The novel variants identified in this study suggest that angiogenesis (VEGFA) and extracellular collagen matrix (FRK/COL10A1) pathways contribute to the development of advanced AMD.

Individuals with neurofibromatosis type 1 (NF1) are prone to develop optic pathway gliomas that can result in significant visual impairment. To explore the cellular basis for the reduced visual function resulting from optic glioma formation, we employed a genetically engineered mouse model of Nf1 optic glioma (Nf1+/−GFAPCKO mice). We performed multi-modal functional and structural analyses both before and after the appearance of macroscopic tumors. At 6 weeks of age, prior to obvious glioma formation, Nf1+/−GFAPCKO mice had decreased visual evoked potential amplitudes and increased optic nerve axon calibers. By 3 months of age, Nf1+/−GFAPCKO mice exhibited pronounced optic nerve axonopathy and apoptosis of neurons in the retinal ganglion cell layer. Magnetic resonance diffusion tensor imaging showed a progressive increase in radial diffusivity between 6 weeks and 6 months of age in the optic nerve proximal to the tumor indicating ongoing deterioration of axons. These data suggest that optic glioma formation results in early axonal disorganization and damage that culminates in retinal ganglion cell death. The Nf1+/−GFAPCKO mice provide a useful model for defining mechanisms of visual abnormalities in children with NF1 and lay the foundations for future interventional studies aimed at reducing visual loss.

The GDNF family ligands (GFLs: GDNF, NRTN, ARTN, and PSPN), interact with GDNF family receptors (GFRαs) and activate intracellular signaling through the Ret receptor tyrosine kinase. To characterize the role of Ret signaling in retinal activity, we examined Ret hypomorphic and Ret conditional mice using electroretinography. We found that aberrant Ret function resulted in markedly diminished scotopic and photopic responses. Using mice deficient in individual GFLs, we found that only NRTN deficiency led to reduced retinal activity. To determine the potential target cell-type for NRTN, we examined the retinal expression of its coreceptors (GFRα1 and GFRα2) and Ret using mice expressing fluorescence reporter EGFP from their respective loci. We found robust GFRα1 and Ret expression in horizontal, amacrine, and ganglion cells, whereas GFRα2 expression was only detected in a subset of amacrine and ganglion cells. In contrast to previous studies, no expression of GFRα1, GFRα2, or Ret was detected in photoreceptors or Müller cells, suggesting these cells are not directly affected by Ret. Finally, detailed morphologic analyses of retinas from NRTN- and Ret-deficient mice demonstrated a reduction in normal horizontal cell dendrites and axons, abnormal extensions of horizontal cell and bipolar cell processes into the outer nuclear layer, and mislocalized synaptic complexes. These anatomic abnormalities indicate a possible basis for the abnormal retinal activity in the Ret and NRTN mutant mice.

Purpose

To determine whether the complement factor H (CFH) Y402H variant is associated with specific age-related macular degeneration (AMD) clinical phenotypes.

Design

Retrospective, case-control study.

Methods

188 Caucasian subjects with AMD and 189 control subjects were genotyped for the T-to-C polymorphism in exon-9 of the CFH gene by restriction-fragment length analysis and DNA sequencing using genomic DNA from mouthwash samples. AMD phenotypes were characterized by clinical examination, fundus photography, and fluorescein angiography.

Results

Heterozygosity for the at-risk genotype (TC) increased the likelihood for AMD 2.1-fold (95% CI 1.3–3.3) while homozygosity for the genotype (CC) increased the likelihood for AMD 6.5-fold (95% CI 3.4–12.5) in our population. The C allele was significantly associated with predominantly classic choroidal neovascularization (OR 2.01, 95% CI 1.34–3.30). Neovascular lesion size was similar among the three genotypes (p=0.67).

Conclusions

The Y402H CFH variant carried a significantly increased risk for developing AMD in our population. Genotype/phenotype correlations regarding choroidal neovascular lesion type were observed