A complex formula of both environmental and genetic mechanisms may work collectively to trigger myopia development, scientists venture, after an international study pinpoints new genetic cues.
Researchers with the Consortium for Refractive Error and Myopia (CREAM) at Johannes Gutenberg University Mainz in Germany uncovered nine new genetic risk factors in myopia development by studying the disorder's connection with education level.
Published April 6 in the journal Nature Communications, the meta-analysis used 34 European and Asian studies—spanning more than 50,000 adults—to identify genetic mutations expressed as a factor of education level, given that educational attainment is generally considered a proxy for near work activity. Their work identified nine novel genetic loci associated with refractive error: three among populations of Asian descent and six among Europeans, in addition to confirming known associations at 17 previously published loci.
These genetic variants are associated with proteins that perform crucial roles in the transmission of signals within the eye, according to the university news release. One such gene, GABRR1, is particularly interesting as it is responsible for the neurotransmitter, gamma-aminobutyric acid (GABA) in the eye, which previous studies have linked to greater activation in myopic eyes. This meta-analysis supported that role, as well.
Although myopia development remains an intricate puzzle, the study's authors write that they hope these new genetic targets will help further therapeutic interventions for myopia and spur further work.
Myopia—nearsightedness, colloquially—affects nearly 30% of the U.S. population, typically first occurring in school-age children and progressing until about age 20. Hereditary factors often control the growth and development of the eye; however, recent evidence suggests factors including near-work or even an 'outdoor effect' may impact ability to focus clearly.
The exact cause of myopia is unknown, and that's why research, such as this CREAM study, proves so beneficial, says Jeffrey Walline, O.D., Ph.D., AOA Contact Lens & Cornea Section (CLCS) chair, and associate dean for research at The Ohio State University College of Optometry.
"Scientists believe that there may be a genetic influence on environmental cues to myopia development, but that has rarely been found to be true, until now," Dr. Walline says, reviewing the study. "This large meta-analysis may have found the genetic-environment interaction by identifying genes that regulate visual signals potentially associated with myopia. The results are very preliminary, but deserve to be more fully investigated."
The publication highlights a fascinating analytic technique to identify associations between genetic markers related to the development of myopia and the impact of environmental factors on the expression of these genetic factors, says Christopher J. Quinn, O.D., AOA vice president.
"This will allow researchers to focus their efforts on these specific targets to unravel how and why myopia develops," Dr. Quinn says.
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