Pooled GWAS identifies a novel gene: OR52B4 influencing anti-VEGF treatment response in Age related macular degeneration

Abstract

Purpose : Anti-Vascular endothelial growth factor (anti-VEGF) is a key treatment for neovascular AMD (nAMD) but its response is variable. This variability is likely to be, in part, due to genetic heterogeneity; although known AMD risk associated genes have been inconclusive in explaining this response. We sought to use a pooled genome wide association study (GWAS) to identify genetic variants that might explain this response.

Methods : A total of 297 nAMD patients, each received 3 monthly ranibizumab injections followed by an inject and extend protocol. Patients were divided into non-responders, (loss of ≥5 EDTRS letters visual acuity (VA)) and the rest were responders following 6 months of ranibizumab treatment. Six separate equimolar DNA pools (3 for responder, 3 for non-responders) based on baseline VA underwent genotyping with the Illumina HumanOmni5-Quad Beadchip array. A pooled GWAS was carried out comparing responders vs non-responders for the three baseline VA categories and results were combined in a meta-analysis via a custom pipeline.Significant SNPs underwent individual genotyping in the same patient cohort. Three validated SNPs were then replicated in a second ranibizumab treated nAMD cohort consists of 376 patients. Meta-analysis on both cohorts was performed using METAL.

Results : Following GWAS, 44 SNPs; of which 37 associated at genome-wide significance, 2 in pharmagenes P<5x10^-5 and 5 missense changes P<5x10^-4 were selected for validation. Three SNPs; rs4910623, rs323085, rs10158937, remained significant (P = 8.3x10^-5, P = 6.4x10^-4, P = 6.4x10^-3 respectively) with response/no response to ranibizumab at 6 months. These 3 SNPs were assessed in a second replication cohort, SNP rs4910623 in the promoter region of the Olfactory Receptor, Family 52, Subfamily B, Member 4 (OR52B4) was significantly associated with treatment outcome at 6 months (P=4.6x10^-2) and also at 3 months (P < 0.001). Meta-analysis of both cohorts confirmed association of rs4910623 with poor VA outcome at 3 (P = 6.9x10^-6) and 6 months (P = 2.4x10^-5) of ranibizumab treatment.

Conclusions : We identified a novel variant rs4910623 in the OR52B4 gene associated with poor VA outcome following ranibizumab treatment in nAMD. The OR52B4 gene encodes a G protein-coupled receptor suggesting that other non VEGF biological pathways may also be involved in response to anti-VEGF treatments.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.