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Genetic Testing for Age Related Macular Degeneration: Are We There Yet?

Age-related macular degeneration (AMD) is a degenerative condition of the retina, causing damage to the macula: a small area of the retina responsible for your sharp, central vision.

Who is affected?

Approximately 1 in 5 people over the age of 75 are affected.  It is a leading cause of vision loss and blindness in people over the age of 60 in the US.  Risk factors include age, lifestyle factors such as smoking, race (AMD is more common among Caucasians than among African-Americans or Hispanics/Latinos), and family history due to a genetic component.

How is AMD inherited?

AMD does not have a straightforward inheritance pattern.   This genetic component is complex and currently being studied.  Since 2005, several genetic variants associated with AMD have been identified.  The discovery of such genetic variants has led to the development of commercial genetic testing to further predict an individual’s risk of developing advanced AMD. 

Can office based genetic tests help you?

Two commercially available genetic tests do so by incorporating clinical information from the individual’s retinal exam and non-genetic risks with his or her genetic profile.  With such testing come various considerations that make genetic testing for AMD controversial.  Firstly, the currently available genetic tests for AMD have been validated based on data from Caucasian populations.  Therefore, the reliability of these tests in individuals of other ethnicities is unclear.  Secondly, it has previously been shown in studies that clinical exam findings are the strongest predictor of disease progression1,2.  Using the AREDS Simplified Severity Score3, an approximate percentage risk of developing advanced AMD in one eye over 5 years can be predicted. 

Genetic testing attempts to expand and further individualize this information and provides a percentage range of risk of developing advanced AMD.  However, given the ability to predict risk as outlined above, the level of information provided, particularly, in those with no or minimal clinical evidence of AMD, appears limited.  Thirdly, and most importantly, since there is no proven advantage in prevention or treatment of AMD based on genetic testing, the utility of the information gained from genetic testing is unknown. Finally, it is currently unclear and unproven whether the results from genetic testing lead to improved visual outcomes for patients. 

What’s the bottom line?

The American Academy of Ophthalmology has advised physicians, outside of research studies, against genetic testing for complex eye disorders, including AMD, “until treatment or surveillance strategies can be shown to be of benefit to individuals with specific, disease-associated genotypes…4  Therefore, we do not advocate the used of office based genetic testing for AMD at this time, however, we look forward to the near future when this may prove more beneficial for patient care.

References:

1. Klein ML, Francis PJ, Ferris FL 3rd, Hamon SC, Clemmons TE. Risk assessment Model for Development of Advanced Age-Related Macular Degeneration. Arch Ophthalmol 2011 Dec;129(12):1543-50.

2. Seddon JM, Reynolds R, Maller J, Fagerness JA, et al.  Prediction Model for Prevalence and Incidence of Advanced Age-related Macular Degeneration Based on Genetic, Demographic, and Environmental Variables.  Invest Ophthalmol & Vis Sci 2009 May;50(5):2044-53

3. Ferris FL, Davis MD, Clemons TE, et al. A simplified severity scale for age-related macular degeneration: AREDS Report No. 18. Arch Ophthal 2005;123:1570-1574.

4. American Academy of Ophthalmology News Release, November 11, 2012.