Introduction:
Myopia is one of the most prevalent visual impairments especially in childhood. Regarding global prevalence of myopia, approximately 50% of the global population will suffer from myopia by the end of 2050. Both genetics and environmental factors such as near work and outdoor time play crucial roles in the myopia. Although environmental factors along with genetic predisposition are associated with the increasing prevalence of myopia amongst children, the mechanism through which they act is moderately understood. An epigenetic event such as
DNA methylation could be one of the mechanisms through which these environmental factors influence the development of myopia.Description: A considerable amount of research has been conducted on the molecular determinants of myopia. GWAS studies of refractive error have identified more than 100 gene loci with a high degree of concordance between studies. However, there have been very few studies investigating whether epigenetic changes may be involved in the myopia. An animal study showed that eyes with refractive error had a higher frequency of scleral
DNA methylation at the COL1A1 promoter and a reduced level of COL1A1 mRNA. In the recent study ofepigenome-wide association study among children, researchers identified five CpG sites that associated with early-onset myopia. The genomic loci for these CpG sites are an intergenic region on 8p23, a region near the ARL1 gene on 12q23.2, and regions within the FGR, PQLC1 and KRT12 genes. In addition, early environmental exposures such as stress, or environmental light, could have an effect similar to air pollution, cigarette smoking or other environmental factor influencing the epigenome in other diseases.Conclusion: Currently there are limited epigenetic studies of myopia risks. Examination of epigenetic markers will be providing novel insights into the etiology of myopia, and modification of reversible, environmental factors would be influence the refractive error outcome.