Abstract: The disease burden of diabetic retinopathy (DR) is tremendous around the world. While DR is correlated with hemoglobin A1c (HbA1c) and duration of diabetes, genetic differences likely account for variation in susceptibility to DR. DR is a polygenic disorder with demonstrated heritability. However, linkage and admixture analyses, candidate gene association studies, and genome-wide association studies (GWAS) have not identified many loci for DR that can be consistently replicated. Larger, collaborative, multi-ethnic GWAS are needed to identify common variants with small effects. Rigorous defining of controls groups as patients with a long duration of diabetes without DR, and case groups as patients with severe DR will also aid in finding genes associated with DR. Replication in independent cohorts will be key to establishing associated loci for DR. Investigations of mitochondrial DNA and epigenetics in DR are ongoing. Whole exome sequencing presents new opportunities to identify rare variants that might be implicated in DR development. Continued research in the genetic epidemiology of DR is needed, with the potential to elucidate pathogenesis and treatment of an important disease.

Abstract: As a complex disease, myopia is the most common eye disease worldwide. Many myopia susceptibility genes or variants have been successfully identified in the past years by genome-wide genetic association studies (GWAS), which focus mainly on the single-nucleotide polymorphisms. Little attention has been paid to examine the role of copy number variations (CNVs) in refractive error and myopia. This study adopted a systematic strategy to investigate the role of CNVs in high myopia. In the discovery phase, a pilot GWAS suggests putative CNVs for follow-up. Multiplex ligation-dependent probe amplification was then used to quantify the copy number of 89 CNV segments in 737 case-control samples in the second phase and then 24 top-ranking CNVs in a second group of 1,029 case-control samples in the final validation phase. This validation phase identified 22 significant CNVs. Further work is needed to examine the role of these few CNVs in myopia development.