Genetic bases for glaucoma.

Glaucoma is the leading cause of visual impairment and blindness throughout the world. Primary open angle glaucoma (POAG; MIM 137760) is the main type of glaucoma in most populations, and more than 20 genetic loci for POAG have been reported. Only three causative genes have been identified in these loci, viz. myocilin (MYOC), optineurin (OPTN), and WD repeat domain 36 (WDR36). However, mutations in these genes account for only a small percentage of the patients with POAG. Some of these glaucoma cases have a Mendelian inheritance pattern, and a considerable fraction of the cases result from a large number of variants in several genes each contributing small effects. Glaucoma is considered to be a common disease such as diabetes mellitus, coronary disease, Crohn disease, and several( )common cancers. The main technological approaches used to identify the genes associated with glaucoma are the candidate gene approach, linkage analysis, case-control association study, and genome-wide association study. Association studies have found about 27 genes related to POAG, but the glaucoma-causing effects of these genes need to be investigated in more detail. The current trend is to use case-control association studies or genome-wide association studies to map the genes associated with glaucoma. Such studies are expected to greatly advance our understanding of the genetic basis of glaucoma, and to provide information on the effectiveness of glaucoma therapy. This review gives an overview on the genetic aspects of glaucoma.