Just a quick glance at haredi (ultra-Orthodox) yeshiva boys who spend most of their waking hours from childhood through adulthood studying Torah and Talmud shows that almost all of them have eyeglasses due to nearsightedness. Does that mean that overexerting your eyes from childhood causes myopia (nearsightedness)?
Researchers led by Dr. Jeremy Guggenheim of Cardiff University in Wales and just published in the open-access journal PLOS Genetics – under the title “Education interacts with genetic variants near GJD2, RBFOX1, LAMA2, KCNQ5 and LRRC4C to confer susceptibility to myopia” offer a somewhat different explanation. The team of researchers found five genetic variants that increasingly raise a person’s risk of becoming nearsighted the longer they stay in school.
Nearsighted vision is associated with a range of eye disorders, making it a leading cause of irreversible vision impairment in older individuals. People often become nearsighted as children, however, and the condition appears to result from a mix of genetics, too little time spent outdoors and many years of education.
Genetic studies have identified more than 450 genetic variants associated with an increased risk of nearsightedness, but few have been shown to increase risk specifically in people with the associated lifestyle factors.
In the study, researchers used genetic and health data from more than 340,000 participants with European ancestry. They performed a genome-wide study to identify genetic variants that make people more susceptible to becoming nearsighted in combination with intensive schooling. However, very few genetic variants had been found that conferred an increased risk of myopia specifically in individuals exposed to higher levels of lifestyle risk factors.
“Here, we leverage statistical features expected for variants with gene-environment interaction effects and harness the large sample size of UK Biobank to identify five genetic variants that confer a progressively increased risk of myopia in individuals who spent increasing years in education,” they wrote.
Five genetic variants
Of the five genetic variants that progressively increased the risk of becoming nearsighted for individuals three of these variants were previously unknown, while two were found in studies of East Asian cohorts, where about 80% of children become nearsighted. By comparison, about 30% of children develop nearsightedness in the West. Two of the variants replicate findings reported in East Asian cohorts, while the other three variants were unique.
“This work provides insight into the biological pathways through which genes and lifestyle interact to cause myopia,” they concluded. “These findings provide new insights into the biological pathways that cause nearsightedness, but more research is needed to understand how those pathways interact with lifestyle factors to cause the condition.”