Age-Related Macular Degeneration: Genetics and Biology

The Role of SNPs in IL1RL1 and IL1RAP Genes in Age-related Macular Degeneration Development and Treatment Efficacy

BACKGROUND

Age-related macular degeneration (AMD) affects the central part of the retina and causes blindness. In developed countries, AMD occurs in people over 50 years old. Important factors for AMD pathogenesis are an immune response, inflammation, and genetic factors. This study aimed to determine the impact of IL1RL1 rs1041973 and IL1RAP rs4624606 single nucleotide polymorphisms (SNPs) on the occurrence of AMD and the outcome of treatment with aflibercept and bevacizumab.

PATIENTS AND METHODS

563 patients with AMD and 281 healthy candidates were evaluated. Patients with exudative AMD were treated with intravitreal bevacizumab and aflibercept and, after 6 months based on the changes in best-corrected visual acuity and central macular thickness, were classified as 'responders' or 'poor-responders'. Genotyping of IL1RL1 rs1041973 and IL1RAP rs4624606 was accomplished using real-time PCR. Age was compared using the Mann-Whitney U-test. Categorical data (gender, genotype, and allele distributions) compared between groups using the χ² test or the Fisher's exact test. Associations of gene polymorphisms were calculated using logistic regression analysis with adjustment for age in exudative and atrophic AMD analysis. An adjusted significance threshold for multiple comparisons α=0.025 was applied.

RESULTS

Statistically significant differences in the distribution of IL1RAP rs4624606 genotypes (TT, TA and AA) were found between males with atrophic AMD and controls: 50%, 42.9% and 7.1% vs. 69.7%, 30.3% and 0%, respectively, p=0.015. Moreover, we found that 'responders' had a significantly better best-corrected visual acuity than 'poor-responders' before treatment (p=0.032). The central macular thickness was significantly lower in exudative AMD patients with IL1RL1 rs1041973 AA genotype than in wild type and heterozygous (CC+CA) genotype carriers before treatment (p=0.017).

CONCLUSION

IL1RAP rs4624606 may be associated with atrophic AMD in males while IL1RL1 rs1041973 may play a protective role against macular thickening in exudative AMD patients.

Views of ophthalmologists on the genetics of age-related macular degeneration: Results of a qualitative study

Background

Age-related macular degeneration (AMD) is the leading cause of blindness in industrialized countries. It is a multifactorial disease of the retina modified by environmental/individual (e.g. smoking) and genetic factors. 34 independent genomic loci are associated with the risk to develop AMD; an interaction between smoking and genetics is currently investigated. It is unclear how the knowledge on the strong genetic component has entered the knowledge base of practicing ophthalmologists, and how they inform and counsel their (AMD) patients about it. In this study, we explore the ophthalmologists’ view on AMD genetics, and their inclination towards communicating genetic risks to patients.

Methods

We recruited a purposive sample of thirty German ophthalmologists (office based: n = 15, hospital employees: n = 15, f:8/30), who took part in a recorded semi-standardized interview. Transcripts were analyzed using content analysis.

Results

The majority of office-based ophthalmologists claimed to be unfamiliar with genetics of AMD, in contrast to hospital-affiliated ophthalmologists. Both office and hospital ophthalmologists were convinced that genetics lacks practical relevance in everyday patient care. Many withhold information on heritability or genetic background of AMD from patients and their relatives, for fear of unsettling those individuals. The relevance of the genetic component of AMD or an individuals’ high genetic risk for prevention, e.g. screening or lifestyle modifications in persons with adverse genetic profile, was rated low.

Conclusion

Developing genetic educational programs tailored to the routine care of ophthalmologists may be indicated, as well as a better two-way communication between research and practice. Exploring patient views about their expectations to being informed about genetic disease etiology, or about their individual risk, would help inform communication strategies.

Genome-wide association study of neovascular age-related macular degeneration in the Thai population

We performed a genome-wide association study on 377 cases of neovascular age-related macular degeneration (AMD) and 1074 controls to determine the association of previously reported genetic variants associated with neovascular AMD in the Thai population. All patients were of Thai ancestry. We confirmed the association of age-related maculopathy susceptibility 2 (ARMS2) rs10490924 (P=7.38 × 10-17), HTRA1 rs11200638 (P=5.47 × 10-17) and complement factor H gene (CFH) rs800292 (P=2.53 × 10-8) with neovascular AMD, all loci passing the genome-wide significance level (P<5.22 × 10-8). We also found association of the previously reported CFH rs10737680 (P=1.76 × 10-6) locus in the discovery sample. Two loci not previously reported to be associated with neovascular AMD were selected for replication in 222 cases and 623 controls. The loci included LINCO1317 rs6733379 and rs2384550 on chromosome 12. LINCO1317 rs6733379 (P=3.85 × 10-2) remained significantly associated with neovascular AMD after replication. In conclusion, we confirm that ARMS2, HTRA1 and CFH variants are associated with neovascular AMD in the Thai population. Findings from this study also suggest that variants contributing to the susceptibility of neovascular AMD in the Thai population are mostly similar to other Asians with additional local genetic risks that may specifically be identified in Thai population.

Pharmacogenetic Aspect of Intravitreal Ranibizumab Treatment in Neovascular Age-Related Macular Degeneration: A Five-Year Follow-Up

PURPOSE

This study aims to evaluate the role of complement factor H (CFH) in response to intravitreal ranibizumab (IVR) treatment, which is administered to patients with neovascular age-related macular degeneration (nAMD).

METHODS

In this retrospective study, 90 nAMD patients' 90 eyes were evaluated. IVR was injected once a month for three consecutive months, and then, patients were followed up for five years by using pro re nata method.

RESULTS

Average visual acuity (BCVA) values in TT group for the third, fourth and fifth years were found to be significantly higher than those in TC and CC groups, while average BCVA values in TC group were significantly higher than those in CC group (all p = .000 < .0167).

CONCLUSION

Patients with CFH TT genotype responded significantly better to treatment after third year, while patients with CC genotype had a poorer response to IVR.