Making an analogy
“We can consider an analogy between glaucoma and diseases, such as breast cancer,” Dr. O'Brien said. “Not so long ago, a person diagnosed with breast cancer simply had breast cancer. Now we know that breast cancer is a wide array of phenotypically and genetically distinct diseases.”
Knowledge of the genetics of breast cancer lets clinicians use precision medicine to treat the disease more effectively than ever, she explained.
“We are learning how to inhibit cancer-promoting pathways that shouldn’t be turned on or to kick-start inhibitory pathways that have been turned off,” Dr. O'Brien added. “That is the goal in glaucoma, to discover the specific pathways that underlie specific kinds of disease, then find ways to change that messaging in cells.”
The POAAGG study population consists of self-identified African Americans aged 35 years and older in the Philadelphia region. Every participant receives a clinical exam that includes a complete glaucoma evaluation and interview. Glaucoma cases, suspects, and controls are determined by glaucoma specialists based on specific clinical criteria.
Glaucoma suspects are particularly important. Some suspects have progressed to cases over the study duration, Dr. O’Brien noted.
“We want to look at the genetic risk factors for rapid progression,” she explained. “We know that in African American populations a good proportion of patients present at a younger age than we would expect in the general U.S. population and progress more rapidly.
“Our center is located in a predominantly African American neighborhood, and our neighbors are walking in already blind from glaucoma,” she added.
POAAGG has already enrolled more than 8,000 African American patients in the Philadelphia area. The 5-year study was launched in April 2014.
“African Americans are the group most adversely affected by POAG, yet they are the least-well studied,” Dr. O’Brien noted. “Only 3% of samples for all genome-wide association studies have been African American, with the vast majority of samples being European. This study is a first step to remedy a lack of understanding and move toward more effective screening, diagnosis, and treatment of POAG.”