In a new study, researchers have found new evidence that there is an underlying link between degeneration of the eye and brain.
They found that genetic variation at a beta-amyloid gene was strongly linked to increased risk of Primary Open Angle Glaucoma (POAG), the most common form of glaucoma and the leading cause of irreversible blindness worldwide.
The association was identified specifically in people with African ancestry. The high-risk variant was common in African populations (around 20%), but essentially absent in all other ancestral groups.
The findings from this research confirmed a common suspicion that glaucoma may not simply be an eye disease, but also linked to degeneration of the brain.
The research was conducted by a global team led by Singapore and the United States.
According to the team, two lines of evidence were established—First, genetic variation at a beta-amyloid gene family was observed to be significantly associated with POAG risk.
Second, beta-amyloid deposits were also strongly increased in the eye and brain tissues of patients with POAG compared to unaffected individuals.
This links degeneration of the eye to possible degeneration of the brain as beta-amyloid is one of the best-known causes for nerve cell death in Alzheimer’s disease and dementia.
Another recent study on a large multi-ethnic sample, the Genetic Epidemiology Research On Adult Health & Aging (GERA) cohort in the U.S., confirmed the highest prevalence of POAG in African ancestry individuals (16.1%) compared to East Asians (9.9%) and Europeans (7.4%).
However, African populations have been understudied and underrepresented in genomic research.
This is despite our understanding that modern humans originated in Africa approximately 200,000 years ago, and 99% of the human evolutionary experience has been in Africa.
African populations hold a treasure trove of unexplored genomic information which could provide solutions to combat various diseases, including glaucoma.
Hence, the team studied POAG in Africans and African-descent populations to obtain biological and clinical insights, which may have been unavailable in European and Asian studies.
The JAMA study on African populations presented new findings that are expected to change the way researchers perceive glaucoma.
Scientists have also begun to look for neuroprotective mechanisms, which could illuminate new ways to treat the disease.
The team says these findings are crucial in efforts to pinpoint why certain groups of people suffer from severe glaucoma, particularly early on in life.
It also suggests that degeneration of the eye and brain could be mechanistically related. This research may lead to solutions to slow down disease onset and lower disease severity.
The study is published in the Journal of the American Medical Association (JAMA).
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