Macular degeneration and genetics

Macular degeneration is an eye disease that affects millions of people worldwide. Although age is a major risk factor, genetics also plays a role in its development. In fact, some forms of macular degeneration are related to specific genetic mutations, which can be inherited. 

If you want to know in depth what connection exists between macular degeneration and genetics, what this disease consists of and what its symptoms are, keep reading.

What is macular degeneration?

Age-related macular degeneration (AMD) is a degenerative eye disorder characterized by the slow destruction of central and sharp vision. As a result, it becomes increasingly difficult to do everyday tasks such as reading or viewing details.

It’s caused by damage to the blood vessels that supply the macula, the central part of the retina, which is responsible for central vision and is composed of two pigments (lutein and zeaxanthin) that help to make vision sharper and more detailed.

Its exact cause is unknown, but it’s known that the patient’s age is the main non-genetic risk factor for the development of this condition. It’s most commonly diagnosed in people over sixty years of age. Currently, macular degeneration is the leading cause of legal blindness in people of this age [1].

Although central vision is completely lost, patients with macular degeneration keep their peripheral vision intact. This means that, for example, if they look at a watch, they can see the numbers perfectly well, but they will not be able to see the hands.

There are two types of macular degeneration: dry and wet. Dry AMD is usually the first stage of this eye disorder and has a slower course. It occurs when damaged blood vessels become thin and fragile and localized thickening, consisting of small yellow deposits, begins to form.

On the other hand, wet macular degeneration occurs in only 10% of people diagnosed with this disorder. In this case, abnormal and particularly fragile new blood vessels grow under the macula and leak blood and fluid. This type causes the greatest vision loss in patients with AMD [2]. Its development is faster and the prognosis is worse [1].

Symptoms of macular degeneration

In the early stages of the disease there are usually no symptoms, but as it’s a progressive disease, symptoms appear and worsen over time. Among the most characteristic symptoms are [2, 3]:

• Blurred central vision. There is a slight blurring of objects, which may also appear opaque or their colors may appear dull.
• Black spots in the central vision, which usually remain fixed and become larger and darker.
• Straight lines that twist. Looking at a straight line may give the sensation that it is wavy or twisted.
• Need for light. You may need more light than before to read or perform certain activities. It is even increasingly difficult to see in low light conditions.

<h2>Macular degeneration and genetics<h2>

Approximately 70% of the risk of macular degeneration is related to genetic variants. A multitude of scientific studies have reported more than 25 genes linked to an increased risk of AMD. 

These genes have diverse functions, including regulation of the complement system. This enzymatic cascade helps defend against infection and plays a key role in immune response, inflammation and maintenance of homeostasis, and many researchers point to a link between inflammatory and immune mechanisms and macular degeneration. Other genes associated with an increased risk of this disease are related to lipid and cholesterol metabolism, and to the regulation of angiogenesis (blood vessel formation) and extracellular matrix deposition.  All of them are associated with the onset, progression and involvement of both eyes at different stages of the disease [3].

Despite having such a strong hereditary component, is also necessary a combination of environmental factors or bad health habits, such as smoking, to trigger the process of macular degeneration. That’s why quitting these bad habits as soon as possible is a good way to prevent the disease.

But, nowadays, thanks to scientific advances related to genetics, there’s also another way to prevent the disease or, at least, to be aware of the risk of suffering from it and to be able to take the necessary changes in one’s lifestyle: genetic tests.

At 24Genetics we have the latest technology for the development of this type of tests. With the DNA health test you’ll be able to know your predisposition to develop macular degeneration and more than two hundred other diseases. Knowledge and prevention are the best weapons to fight against the onset of many pathologies.

Performing a genetic test is very simple: you only need a saliva sample, which you can collect in the comfort of your home, and send it to our laboratory for analysis. You will obtain a detailed report with very interesting genetic information for the prevention and success of medical treatments. Get your test now!

Bibliography

[1] Age-related macular degeneration – Dr. Alfredo García Layana. Director Department of Ophthalmology – Clínica Universidad de Navarra [accessed Feb. 2023]Available at: https://www.cun.es/enfermedades-tratamientos/enfermedades/dmae-degeneracion-macular

[2] MedlinePlus in Spanish [Internet]. English version reviewed by: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, CA, David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team – Age-Related Macular Degeneration [accessed Feb. 2023] Available at: https://medlineplus.gov/spanish/ency/article/001000.htm

[3] Genetic testing for macular degeneration – Macula Retina Association [published Apr. 2019; accessed Feb. 2023] Available at: https://www.macula-retina.es/pruebas-geneticas-para-la-degeneracion-macular/