Seyedeh M. Zekavat, Sayuri Sekimitsu, Tobias Elze, Pradeep Natarajan, Lucian V. Del Priore, Nazlee Zebardast, Ayellet V. Segrè, Janey L. Wiggs, Hongyu Zhao, Jay C. Wang, and Yixuan Ye
IntroductionAge-related macular degeneration (AMD) is a blinding condition for which there is currently no early-stage clinical biomarker. AMD is characterized by thinning of the outer retina and drusen formation leading to thickening of the Bruch’s membrane and RPE complex, but the timing between these two events, as well as the role of genetic variants in these processes, are unclear. Here, we jointly analyzed genomic, electronic health record, and optical coherence tomography (OCT) data across 44,823 individuals from the UK Biobank to characterize the epidemiological and genetic associations between retinal layer thicknesses and AMD.MethodsThe Topcon Advanced Boundary Segmentation algorithm was used for automated retinal layer segmentation. We associated 9 retinal layer thicknesses with prevalent AMD (present at enrollment) in a logistic regression model, and with incident AMD (diagnosed after enrollment) in a Cox proportional hazards model. Next, we tested the association of AMD-associated genetic alleles, individually and as a polygenic risk score (PRS), with retinal layer thicknesses. All analyses were adjusted for age, age2, sex, smoking status, and principal components of ancestry.ResultsPhotoreceptor segment (PS) thinning was observed throughout the lifespan of individuals analyzed and accelerated at age 45, while retinal pigment epithelium and Bruch’s membrane complex (RPE+BM) thickening started after age 57. Each standard deviation (SD) of PS thinning and RPE+BM thickening were associated with prevalent AMD (PS: OR 1.37, 95% CI 1.25-1.49, P=2.5×10−12; RPE+BM: OR=1.34, 95% CI 1.27-1.41, P=8.4×10−28) and incident AMD (PS: HR 1.35, 95% CI 1.23-1.47, P=3.7×10−11; RPE+BM: HR 1.14, 95% CI 1.06-1.22, P=0.00024). An AMD polygenic risk score (PRS) was associated with PS thinning (Beta -0.21 SD per 2-fold genetically increased risk of AMD, 95% CI -0.23 to -0.19, P=2.8×10−74), and its association with RPE+BM was U-shaped (thinning with AMD PRSndpercentile and thickening with AMD PRS>92ndpercentile suggestive of drusen formation). The loci with strongest support were AMD risk-raising variantsCFH:rs570618-T,CFH:10922109-C, andARMS2/HTRA1:rs3750846-C on PS thinning, andSYN3/TIMP3:rs5754227-T on RPE+BM thickening.ConclusionsEpidemiologically, PS thinning precedes RPE+BM thickening by decades, and is the retinal layer most strongly predictive of future AMD risk. Genetically, AMD risk variants are associated with decreased PS thickness. Overall, these findings support PS thinning as an early-stage clinical biomarker for future AMD development.