Researchers at Kaiser Permanente identified dozens of new genetic associations for increased risk of age-related cataracts, one of the leading causes of blindness worldwide.
The study, published in the journal Nature Communications, also identified genetic associations that are specific to the risk of cataracts for women. The condition is more common among women and this specific association may help explain why.
The large size of the study, which included data from more than 3.5 million individuals, helped researchers identify many more genetic associations than previously known. This study identified more than 54 genetic associations in dozens of genes, including some that are involved in the development of the lens within our eyes.
While genetics explains some of the risks for developing cataracts, environment, and lifestyle can also play a role. Smoking, eye injuries, and certain medications, for instance, all can increase the risk of developing cataracts. Cataracts tend to develop as we age. Some estimates are that more than half of those over 80 have cataracts or have had surgery to remove them. Cataracts are characterized by a clouding of the lens that can cause blurry vision, a loss of the vividness of color, or the ability to see at night. In more serious cases, cataracts can lead to blindness.
By understanding the associated genes, it can also help identify those at higher risk for the condition. This could allow for earlier treatment, said the author of the paper Hélène Choquet, Ph.D., a research scientist at the Kaiser Permanente Division of Research.
“This is the first step, and we can use this information along with other factors to build predictive models to identify people more likely to develop cataracts,” Choquet said. “If we can screen people before they develop a disease that would help them and their doctors to quickly identify when a cataract is forming.”
Thought to be the largest genetic study of cataracts ever the research included data from more than half a million people drawn from Kaiser Permanente, the UK Biobank, which included about 67,000 with cataracts. The researchers then replicated their findings by using data from more than 3 million, including more than 340,000 with cataracts, from 23andMe who consented to participate in research.
The large study also included data from people of non-European ancestry, which are underrepresented in genetic research. In this case, 37 of the new genetic associations cut across different ancestries. In addition two of the associations were found in just women.
The data came from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort. This cohort includes a group of more than 100,000 Kaiser Permanente Northern California members who volunteered their genetic and medical information for research. GERA is part of the Kaiser Permanente Research Program on Genes, Environment, and Health, which is itself part of the Kaiser Permanente Research Bank. Researchers also used data from the UK Biobank. The UK Biobank contains genetic and health information from about a half-million residents of the United Kingdom. The replication study used data from more than 3 million 23andMe customers who consented to participate in research.
The researchers also looked at the genes identified through this study and analyzed their function in a database with information on how these same genes express themselves in mice. That analysis confirmed that many of the genetic associations identified in the study were also seen in data on gene expression in mouse eye lens tissue.
“If the gene is expressed in the tissue that means it could have a direct relationship to the development of a cataract, which is caused by crystallization of the lens,” Choquet said.
Funding for the study came from several sources including the National Institutes of Health and in particular the National Eye Institute.