Making Biological Sense of Genetic Studies of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a major cause of blindness in older individuals worldwide. The disease is characterized by deposition of drusen between the retinal pigment epithelium (RPE) and Bruch's membrane, RPE atrophy and death of photoreceptors. AMD is a complex disease with multiple genetic and non-genetic risk factors. Genome-wide association studies (GWAS) have identified 52 variants at 34 genetic loci associated with AMD. A majority of the AMD-GWAS variants are present in non-coding region of the genome and could quantitatively impact distinct human traits [called quantitative trait loci (QTLs)] by affecting regulation of gene expression. The integration of different regulatory features, such as open-chromatin regions, histone marks, transcription factor binding sites, with AMD-GWAS can provide meaningful insights into variant's function. However, functional interpretation of variant-gene relationship in AMD is challenging because of inadequate understanding of cell-type specific and context-dependent information in disease-relevant tissues. Here we focus on the role of sequencing-based omic studies in assigning biological meaning to disease-associated variants and genes. We also discuss the methods and model systems that can be utilized to unravel molecular mechanisms of a complex disorder like AMD.