DNA sequencing can help identify people at risk of vision loss

The complement factor H gene plays a big role… find out how

Vision loss is a common condition when people age. Sometimes it happens because of an accident, other times it’s caused by a health condition like diabetes. But the most common cause of vision loss involves a combination of genetic and environmental factors. It’s known as age-related macular degeneration.

This is a condition where a person progressively loses their vision, sometimes resulting in near complete vision loss. For our eyes to see, light has to be focused on the back part of the eye at a spot known as the fovea—a region of the retina that’s densely packed with visual neurons and is critical in forming detailed imagery. Because this part of the eye is so important to our vision, it makes sense that anything that causes a distortion or damage to the fovea will have a noticeable impact on a person’s vision.

Image demonstrating vision loss from the point of view of someone with varying degrees of age-related macular degeneration. This is one of multiple educational images that come with MayoClinic’s GeneGuide.

 

One of the main factors causing damage to the fovea in people with this condition is inflammation1. The eye is one of the few places in our body (along with the brain and inner ear) where the body actively prevents inflammation, which could otherwise distort or damage tissue and have a dramatic effect on vision. To help keep inflammation to a minimum, our body makes a protein known as complement factor H. Importantly, researchers have found that people who inherit genetic factors that affect the complement factor H (CFH) gene—the gene that codes for the complement factor H protein—are more likely to develop age-related macular degeneration later in life1,2.

Studies have shown that multiple genetic factors may contribute to a person’s odds of developing age-related macular degeneration1-3. One variant in particular is strongly associated with this condition. The average risk of developing age-related macular degeneration for a person between the ages of 50-54 is 0.36%, meaning 1 person out of 275 may develop this condition. However, carrying just one copy of this particular variant in the complement factor H gene (known to scientists as rs1061170) can increase a person’s odds of developing age-related macular degeneration by as much as 2.5 times1. The odds go even higher for someone with two copies of the variant, one inherited from each parent1. It’s important to note that even with this increased risk of developing age-related macular degeneration, the majority of people who inherit this variant will not develop vision loss. What these studies do suggest is that genetic sequencing may be able to identify individuals who are at risk of developing this condition and could benefit from preventive action.

 

Genetic testing can help you learn about this condition

Age-related macular degeneration is typically diagnosed in people older than age 55. The progressive nature of this disease means that it can get worse with age, and a person’s likelihood of developing the condition increases the older they get2. But while it develops later in life, there may be actions that you can take earlier to slow its progression and potentially prevent severe vision loss. One such action is to quit smoking. Smoking can have numerous negative effects on a person’s health, and research has shown that people who smoke regularly have an increased likelihood of developing age-related macular degeneration (possibly due to the increased inflammation throughout the body)1,2. The risk of developing age-related macular degeneration in people who are genetically predisposed to it and also smoke is much higher than in people without these risk factors1,2.

Genetic testing can be used to determine who has an increased risk of developing age related macular degeneration. Genetic tests like Mayo Clinic GeneGuide™ are designed to help you understand your risks by assessing your genetic and environmental risk factors. Specifically, Mayo Clinic GeneGuide analyzes your DNA to determine if you’ve inherited two different variants that are associated with age related macular degeneration, one of which is the variant in complement factor H discussed here. This information, combined with details you provide about your lifestyle and environment, is used to help you understand what your odds are of developing this condition later in life.

Scientists are working hard to learn more about age-related macular degeneration, and it’s likely that more genetic factors will be associated with this condition in the coming years. If you’ve been found to have a variant linked to age-related macular degeneration, genetic counselors may be able to help you understand what impact the variant may have, and how to discuss this with your loved ones. Resources to help you find genetic counselors can be found here.

Learn more about Mayo Clinic GeneGuideTM >

 

1García-Layana, Alfredo et al. “Early and intermediate age-related macular degeneration: update and clinical review” Clinical interventions in aging vol. 12 1579-1587. 3 Oct. 2017, doi:10.2147/CIA.S142685

2Maugeri, Andrea et al. “Complement System and Age-Related Macular Degeneration: Implications of Gene-Environment Interaction for Preventive and Personalized Medicine” BioMed research international vol. 2018 7532507. 26 Aug. 2018, doi:10.1155/2018/7532507

3“Genetic insights into age-related macular degeneration: controversies addressing risk, causality, and therapeutics” Molecular aspects of medicine vol. 33,4 (2012): 467-86.

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