Glaucoma results in vision loss due to damage of the optic nerve that is irreversible if undetected or untreated. The most common form of glaucoma is primary open angle glaucoma (POAG). While glaucoma affects all races, persons of African descent are disproportionately affected; studies show African-Americans (AAs) are about four to five times more likely than Caucasian Americans to develop the disease. Glaucoma is the leading cause of irreversible blindness in Americans of African descent, and the second leading cause in all Americans. The lack of understanding about the etiology of POAG impedes our ability to identify and treat it early in its development. Evidence of genetic contribution in the pathogenesis of POAG is well established. Since POAG tends to run in families, it is critical to identify the genetic basis of the disease in order to develop effective therapies for early intervention. While genome wide association studies (GWAS) for glaucoma have been completed for Caucasian populations, evidence from other studies suggests that a GWAS of glaucoma specific genes to the African-American population will yield unique and important findings for both this population and for glaucoma in general. A better understanding of the relationship among the stage of disease, the rate of change, ancestry, and other important risk factors being tracked in the ongoing African Descent and Glaucoma Study (ADAGES) will allow us to evaluate the relationship between genetics, visual loss and structural damage in this high-risk cohort. The scientific plan for this new study focuses on glaucoma in ~2000 African-Americans by detailed phenotyping of new subjects, acquisition of samples from both new and established previously phenotyped study subjects for a repository, establishment of a data coordinating center, and genome wide association studies. The recruitment, enrollment, and phenotyping of both established and new subjects occurs at four clinical centers, University of California (UCSD), New York Eye and Ear Infirmary New York University of Medicine, a private practice in the Atlanta area, and the University of Alabama at Birmingham. UCSD is also the location for the Data Coordinating Center and the Repository with Robert N. Weinreb as Principal Investigator. CSMC will do the genotyping with a GWAS panel of ~2.5 million single nucleotide polymorphisms (SNPs) plus an exome set of ~300,000 SNPs using the Illumina Omni2.5 plus exome platform under the direction of Jerome Rotter and Kent Taylor. CSMC will also provide GWAS and exome data for 3435 controls. Comparison and confirmation of the GWAS and exome SNPs and data associated with glaucoma will be compared and confirmed with the University of Pennsylvania's similar glaucoma study.
Glaucoma is four to five times more likely to occur in persons of African descent, up to fifteen times more likely to cause meaningful visual impairment in this group compared to those of European descent, and the leading cause of blindness in African Americans. The overall goal of 'ADAGES III: Contribution of genotype to glaucoma phenotype in African-Americans' is to complete a genome-wide association study (GWAS) and identify the genes of primary open angle glaucoma in African Americans descent. Identifying glaucoma genes in the high-risk, minority population will lead to improved predictive models for glaucoma diagnosis and progression detection, as well as the discovery of new drug targets for therapies to reduce the visual impact of glaucoma blindness.
