Page 100 - March-2015-Life-in-Naples-Magazine

Macular Degeneration

and Genetics: SHOULD YOU GET TESTED?

Aby Stephen G. Schwartz, MD, MBA DR. STEPHEN G. SCHWARTZ, MD, MBA
ge-related macular degeneration is the
leading cause of irreversible visual loss order to accurately predict whether or not a patient will develop macular degeneration,
among the elderly in the US. The causes so at this time I do not recommend this test to my patients.
of macular degeneration are poorly
understood but the disease does seem to run in Patients who already have macular degeneration may benefit from a specific
families, which suggests that there may be a genetic nutritional supplement, available over the counter under the names AREDS
(or hereditary) component. Genetic testing does (standing for “Age-Related Eye Disease Study”) or AREDS 2. These supplements
exist for macular degeneration. Should patients have contain antioxidants (including lutein or beta-carotene) as well as zinc. There is very
this testing performed? good scientific evidence that AREDS or AREDS 2 supplements reduce the risk of
developing progressive disease in patients who already have macular degeneration.
This is not a straightforward question. There There is some evidence that the supplements do not work equally well in all patients,
are two major types of genetic diseases. The first is and that some of this difference may be predicted by certain genetic risk variants.
called a simple genetic disease, in which there is a
single gene that determines whether or not a person Should patients undergo genetic testing to determine whether they take
develops the disease. If the person has a “normal” AREDS or some other supplement? This is an important question, because some
gene, then no disease develops, but if a patient has recent scientific evidence suggests that genetic testing may be useful in order to
an “abnormal” gene, also called a mutation, then predict which supplements are best for each individual patient. However, this
the disease may develop. Simple genetic diseases recent scientific evidence (suggesting the use of genetic testing prior to starting
include cystic fibrosis, Tay-Sachs disease, sickle cell supplementation) is not as strong as the original clinical trials that demonstrated
anemia, and others. Generally speaking, it makes the efficacy of AREDS and AREDS 2. This is currently a controversial subject
more sense to recommend genetic testing for among ophthalmologists. At this time, I do not recommend the use of routine
patients at risk for simple genetic diseases, because genetic testing in patients with macular degeneration, in order to predict disease
the presence of a mutation suggests a high risk of progression or to guide nutritional supplementation.
developing the disease.
In summary, there is a complex relationship between genetics and certain aspects
The other type of genetic disease is called a of macular degeneration. This is an important area of research, and Bascom Palmer
complex genetic disease, in which there are multiple Eye Institute is participating in a long-range genetics research study to learn more
genes, plus environmental influences, that determine about this relationship. However, at this time, I do not recommend routine genetic
whether or not a person develops the disease. This is testing for patients with macular degeneration.
not a question of “normal” versus “abnormal” genes,
so physicians and scientists generally do not use the
word “mutation” in this situation. Instead, certain
“variants” of genes (often called “risk variants”)
are more likely to be associated with the onset of
disease. Generally speaking, it does not make sense
to recommend genetic testing for patients at risk for
complex genetic diseases, because the presence of
one or more risk variants does not necessarily mean
that a person will develop the disease.

For example, there are at least 19 different
genes that are known to be associated with macular
degeneration. In addition, certain environmental
exposures, including cigarette smoking, and foods
(or vitamins) eaten, play a role. How many “risk
variants,” plus how many environmental exposures,
does it take to develop macular degeneration? At
this time, the answer is unknown. For these reasons,
genetic testing does not give sufficient information in

100 Life in Naples | March 2015