Influence of ROBO1 and RORA on Risk of Age-Related Macular Degeneration Reveals Genetically Distinct Phenotypes in Disease Pathophysiology

Gyungah Jun,Monte J Radeke,Gregory S Hageman,Michael Nicolaou,Nissa Mollema,Margaux A Morrison,Debra A Schaumberg,Yoshihiro Yonekawa,Neena B Haider,Margaret M Deangelis,Lindsay A Farrer,Joan W Miller,Ivana K Kim,Fani Zacharaki,Denise J Morgan,Evangelia E Tsironi,Maria Kotoula ,Jacqueline L Buros ,Ye Yuan

doi:10.1371/journal.pone.0025775

Abstract

ROBO1 is a strong candidate gene for age-related macular degeneration (AMD) based upon its location under a linkage peak on chromosome 3p12, its expression pattern, and its purported function in a pathway that includes RORA, a gene previously associated with risk for neovascular AMD. Previously, we observed that expression of ROBO1 and RORA is down-regulated among wet AMD cases, as compared to their unaffected siblings. Thus, we hypothesized that contribution of association signals in ROBO1, and interaction between these two genes may be important for both wet and dry AMD. We evaluated association of 19 single nucleotide polymorphisms (SNPs) in ROBO1 with wet and dry stages of AMD in a sibling cohort and a Greek case-control cohort containing 491 wet AMD cases, 174 dry AMD cases and 411 controls. Association signals and interaction results were replicated in an independent prospective cohort (1070 controls, 164 wet AMD cases, 293 dry AMD cases). The most significantly associated ROBO1 SNPs were rs1387665 under an additive model (meta P = 0.028) for wet AMD and rs9309833 under a recessive model (meta P = 6×10−4) for dry AMD. Further analyses revealed interaction between ROBO1 rs9309833 and RORA rs8034864 for both wet and dry AMD (interaction P<0.05). These studies were further supported by whole transcriptome expression profile studies from 66 human donor eyes and chromatin immunoprecipitation assays from mouse retinas. These findings suggest that distinct ROBO1 variants may influence the risk of wet and dry AMD, and the effects of ROBO1 on AMD risk may be modulated by RORA variants.

Highlights

Age-related macular degeneration (AMD) is a progressive retinal disease that severely reduces the quality of life
We demonstrated significant association with ROBO1 single nucleotide polymorphisms (SNPs) showing increased risk of wet and early/intermediate dry AMD in a combined cohort of sibling pairs, cases and controls from Central Greece, as well as a prospective case control study from the Nurses’ Health Study (NHS)/ Health Professionals Follow-up Study (HPFS)
We discovered variants from different linkage disequilibrium (LD) blocks that could explain the separate association signals for wet and early/ intermediate dry AMD. This suggests that different regions of this gene may be responsible for risk of the different subtypes of AMD or possibly indicate who may progress to wet or neovascular AMD, which would have implications for therapeutic targets

Summary

Introduction

Age-related macular degeneration (AMD) is a progressive retinal disease that severely reduces the quality of life. The disease occurs in men and women.[1] There are two advanced clinical subtypes of AMD, non-exudative (geographic atrophy) and exudative (neovascular or wet) These advanced subtypes may have different pathophysiologic mechanisms, both can be preceded by the development of drusen (yellow-gray material in Bruch’s membrane) and retinal pigment epithelium (RPE) changes that progress into areas of atrophy, or in the case of wet AMD, the growth of new vessels from the choroid into the sub-RPE or subretinal space. It is this wet AMD, the neovascular subtype, that is responsible for loss of vision in the majority of cases. In light of the involvement of ROBO1 and RORA in eye development, the retina, and our previous expression results, we investigated the association of AMD risk with ROBO1 and the interaction of these two genes

Results

Discussion

Findings

Methods