Abstract
Purpose :
To compare the genetic profiles of patients with different phenotypes of AMD, including bilateral geographic atrophy (GA), vascularized pigment epithelial detachment (vPED) or type-1 CNV, and type-2 exudative AMD (Type 2 CNV) to determine if certain genetic variants are more associated with different clinical phenotypes of advanced AMD
Methods :
Case control study of Caucasian subjects over 50 years of age were phenotyped on the basis of clinical data and assigned to one of three cohorts: neovascular AMD (CNV), vascularized pigment epithelial detachment ( vPED) or Geographic Atrophy (GA). Buccal mucosal swabs from each subject were genotyped with a panel of 12 AMD associated SNPs using a matrix-assisted laser desorption ionization-time of flight mass spectrometry based system, at the Sequenom Center for Molecular Medicine. SNP frequencies were calculated in each group and allelic odds ratios (ORs) were evaluated for significance using Fisher’s exact test.
Results :
Genotype analysis was performed on 53 eyes with GA, 50 eyes with Type-1 CNV, and 51 eyes with Type-2 CNV. Baseline characteristics (age, gender, right eye versus left eye, age, and baseline visual acuity) of the three study groups were well-balanced. Higher frequency of the C3 risk variant rs2230199 (Arg102Gly) was observed in the GA population compared to vPED group (p value 0.04).
Conclusions :
Genetic variants identified in the complement pathway have been implicated in the pathogenesis of many inflammatory diseases. The C3 Gly102 AMD variant has previously been found to be more associated with GA than with CNV (Reynolds 2009) with serum levels of the cleavage component C3a higher in GA patients compared to age- matched controls. C3a binds to the C3a receptor and plays a large role in immune response. The findings from this small study suggest certain genetic variants associated with inflammation might be more associated with GA compared to vPED and CNV. The conclusion of this exploratory study needs further confirmation through more studies with larger sample sizes and correction for multiplicity testing.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.