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.

Epha2, an abundant component of the lens fiber cell membrane, is required for tissue patterning and refractive organization of the lens.

Purpose.

The Epha2 receptor is a surprisingly abundant component of the membrane proteome of vertebrate lenses. In humans, genetic studies have linked mutations in EPHA2 to inherited and age-related forms of cataract, but the function of Epha2 in the lens is obscure. To gain insights into the role of Epha2, a comparative analysis of lenses from wild-type and Epha2−/− mice was performed.

Methods.

Epha2 distribution was examined using immunocytochemistry and Western blot analysis. Lens optical quality was assessed by laser refractometry. Confocal microscopy was used to analyze cellular phenotypes.

Results.

In wild-type lenses, Epha2 was expressed by lens epithelial cells and elongating fibers but was degraded during the later stages of fiber differentiation. Epha2-null lenses retained their transparency, but two key optical parameters, lens shape and internal composition, were compromised in Epha2−/− animals. Epha2-null lenses were smaller and more spherical than age-matched wild-type lenses, and laser refractometry revealed a significant decrease in refractive power of the outer cell layers of mutant lenses. In the absence of Epha2, fiber cells deviated from their normal course and terminated at sutures that were no longer centered on the optical axis. Patterning defects were also noted at the level of individual cells. Wild-type fiber cells had hexagonal cross-sectional profiles with membrane protrusions extending from the cell vertices. In contrast, Epha2−/− cells had irregular profiles, and protrusions extended from all membrane surfaces.

Conclusions.

These studies indicate that Epha2 is not required for transparency but does play an indispensable role in the cytoarchitecture and refractive quality of the lens.

Purpose

To map and identify the genetic defect underlying autosomal dominant cataract segregating in a 5-generation Caucasian American family.

Methods

Genomic DNA was prepared from blood leukocytes, genotyping was performed using microsatellite markers, and logarithm of the odds (LOD) scores were calculated using the LINKAGE programs. Mutation profiling was performed using direct exon cycle-sequencing and restriction fragment analysis. Protein function effects were evaluated using in silico prediction algorithms.

Results

Significant evidence of linkage was obtained at marker D13S175 (maximum LOD score [Zmax]=3.67; maximum recombination fraction [θmax]=0.04) and D13S1316 (Zmax=2.80, θmax=0.0). Haplotyping indicated that the disease lay in the ~170 Kb physical interval between D13S1316 and D13S175, which contained the gene for gap-junction protein alpha-3 (GJA3) or connexin-46. Sequencing of GJA3 detected a heterozygous transition (c.130G>A) in exon-2 that resulted in gain of an Hsp92 II restriction site. Allele-specific PCR amplification and restriction analysis confirmed that the novel Hsp92 II site co-segregated with cataract in the family but was not detected in 192 normal unrelated individuals. The c.130G>A transition was predicted to result in a non-conservative substitution of valine-to-methionine at codon 44 (p.V44M) with damaging effects on protein function.

Conclusions

These data confirm GJA3 as one of the most frequently mutated genes that underlie autosomal dominant cataract in humans, and further emphasize the importance of connexin function in maintaining lens transparency.

Lens opacities, or cataract(s), may be inherited as a classic Mendelian disorder usually with early-onset or, more commonly, acquired with age as a multi-factorial or complex trait. Many genetic forms of cataract have been described in mice and other animal models. Considerable progress has been made in mapping and identifying the genes and mutations responsible for inherited forms of cataract, and genetic determinants of age-related cataract are beginning to be discovered. To provide a convenient and accurate summary of current information focused on the increasing genetic complexity of Mendelian and age-related cataract we have created an online chromosome map and reference database for cataract in humans and mice (Cat-Map).

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

Purpose

Cataracts are a clinically and genetically heterogeneous disorder affecting the ocular lens, and the leading cause of treatable vision loss and blindness worldwide. Here we identify a novel gene linked with a rare autosomal dominant form of childhood cataracts segregating in a four generation pedigree, and further show that this gene is likely associated with much more common forms of age-related cataracts in a case-control cohort.

Methods

Genomic DNA was prepared from blood leukocytes, and genotyping was performed by means of single nucleotide polymorphism (SNP) markers, and short tandem repeat (STR) markers. Linkage analyses were performed with the GeneHunter and MLINK programs, and association analyses were performed with the Haploview and Exemplar programs. Mutation detection was achieved by PCR amplification of exons and di-deoxy cycle-sequencing.

Results

Genome-wide linkage analysis with SNP markers, identified a likely disease-haplotype interval on chromosome 1p (rs707455-[~10 Mb]-rs477558). Linkage to chromosome 1p was confirmed using STR markers D1S2672 (LOD score [Z]=3.56, recombination distance [θ]=0), and D1S2697 (Z=2.92, θ=0). Mutation profiling of positional-candidate genes detected a heterozygous transversion (c.2842G>T) in exon 17 of the gene coding for Eph-receptor type-A2 (EPHA2) that cosegregated with the disease. This missense change was predicted to result in the non-conservative substitution of a tryptophan residue for a phylogenetically conserved glycine residue at codon 948 (p.G948W), within a conserved cytoplasmic domain of the receptor. Candidate gene association analysis further identified SNPs in the EPHA2 region of chromosome 1p that were suggestively associated with age-related cataracts (p=0.007 for cortical cataracts, and p=0.01 for cortical and/or nuclear cataracts).

Conclusions

These data provide the first evidence that EPHA2, which functions in the Eph-ephrin bidirectional signaling pathway of mammalian cells, plays a vital role in maintaining lens transparency.