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Name: Macular Degeneration

Description: Sample casebook 05

This casebook is published and has been read 456 times.

The author of this casebook has identified the following medical topics as being highly relevant to this casebook.

Notes

From Navigenics:

Macular degeneration

  • Fact: Although it does not cause total blindness, macular degeneration can affect your ability to read, drive and recognize people’s faces.
  • Proportion of risk that’s in your genes: 67 percent.
  • What you can do: The damage caused by macular degeneration can’t be reversed, but early detection and treatment may help reduce the extent of vision loss. Taking a genetic test to determine whether you have a genetic predisposition to macular degeneration is a good start.
  • Did you know? Quitting smoking is the most important way to prevent macular degeneration. Being a smoker doubles your risk.

In age-related macular degeneration, tissue in the back of your eye that’s responsible for your most precise vision begins to deteriorate. This causes a blind spot in the center of your visual field; fine newsprint may become harder to read and street signs more difficult to recognize.

About 2 million Americans have macular degeneration, and it is the leading cause of severe vision loss in seniors.

Scientists have identified several common genetic variants that are associated with increased risk of macular degeneration. These variants can cause your risk of developing the health condition to rise steeply, depending on whether you have one or two copies of a risk marker. Our gene test scans your DNA for these genetic risk markers.

Knowing from genetic testing whether you have an inherited predisposition for the disease enables you and your doctor to be alert to symptoms of macular degeneration as they arise, aiding early detection and treatment.

One of the best things you can do for your eye health is to have your vision checked regularly. Another important step in preventing macular degeneration is not to smoke. Smokers are at least two times more likely than non-smokers to have macular degeneration, and are more likely to develop advanced forms of the disease. Various supplements may be appropriate, as well.

 

From deCODEme:

AMD is the most common cause of poor sight in people over 50

Age-related macular degeneration or AMD is a major cause of visual impairment in the United States, with approximately 1.8 million Americans over the age of 50 affected by the disease, and another 7.3 million people with intermediate AMD who are at substantial risk of vision loss. It has been estimated that by 2020 there will be 2.9 million people with advanced AMD in the US.

Mainly the central vision is affected in AMD

As part of the aging process deposits, called drusen, form in the retina of the eye. AMD leads to the deterioration of the retina that is partly due to the excessive accumulation of drusen. The retina is the part of the eye that relays images via the optic nerve to the brain. The centre of the retina is called the macula and is responsible for the detailed central vision that allows people to read, drive, and recognize faces. If the macula starts to break down, areas in the center of the visual field start to look blurred.

The two main types are ‘wet’ and ‘dry’ AMD

AMD can be split into three grades of severity, based on the number and size of the drusen and the appearance of the retina: early, intermediate and advanced, which can be further split into two forms, called wet and dry AMD. Dry AMD is more common than wet AMD, but the latter is responsible for over 80% of cases of severe loss of vision and legal blindness related to AMD. Advanced AMD is primarily a condition affecting individuals after the age of 60.

Genetics contribute significantly to AMD

Genetic factors have been shown to contribute significantly to the development of AMD; for example having first degree relatives with AMD increases the lifetime risk 2-3 fold. Variants in five regions of the genome have been identified that increase the risk of developing AMD: a variant in the CFH gene on chromosome 1, a variant in the ARMS2/HTRA1 genes on chromosome 10, two variants in the C2/CFB genes on chromosome 6 and one variant in the C3 gene on chromosome 19. CFH, C2, CFB and C3 are involved in the immune response and controlling inflammation in the body. Individuals with certain variants in these genes may be at higher risk for inflammation-induced damage to the retina.

deCODEme can calculate your genetic risk of AMD

The deCODEme Complete Scan identifies all the variants listed above and provides an interpretation of the risk for developing AMD in customers of European descent. In East Asians, deCODEme currently identifies risk associated with only a single variant in the ARMS2 gene on chromosome 10. Currently no risk data are available for the variants listed above for people of other ethnicities.

Smoking is one of the main risk factors for AMD

Although it is not clear what causes AMD, a number of factors that may put a person at greater risk for developing AMD have been identified:

     

  • Age: AMD rarely affects those under age 50 and studies show that people over age 60 are at greater risk than other age groups.
  • Gender: White females appear to have higher risk than males.
  • Smoking: Studies have found that current and former smokers have up to twice the risk of developing AMD as non-smokers.
  • Obesity: Studies have suggested a link between obesity and the progression of early- and intermediate-stage AMD to advanced AMD.
  • Genetics: The increased risk of AMD related to family history demonstrates that genetics play a significant role in development of the disease. Individuals with a single relative with AMD are twice as likely to develop the disease, while those with two or more relatives are nearly four times as likely to be diagnosed. The risk is even higher if the affected family members were diagnosed before the age of 65.
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Early diagnosis and prevention are important

Although there is no known cure for either form of AMD, therapies are available that can slow the progression of the disease. Early diagnosis is also an important part of controlling disease progression. People at risk for AMD, including those over the age of 50 and those with a family history of AMD, should have their eyes examined regularly, learn to recognize the signs of AMD, and take steps to reduce their risk for developing AMD.

More information

You can find out more information about AMD by talking with your doctor and visiting these Web sites:

From 23andMe:

Age-related Macular Degeneration is one of the conditions that 23andMe analyzes. Our service includes the following information:

  • An estimate, based on currently available information, of whether your genetic risk for Age-related Macular Degeneration is higher or lower than average.
  • Your results at 3 markers.
  • Background information on Age-related Macular Degeneration and a list of counselors, links and support groups in your area.

About Age-related Macular Degeneration

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss in the western world among people over 60. The disease affects the central part of the retina, which is critical for activities like reading, driving, or even recognizing faces. AMD can develop so slowly that some people may not even realize they have it, while others suffer a rapid loss of sight in both eyes. More than 1.7 million people in the U.S. have AMD (about 7% of people over 75). It is estimated that by 2020, almost 3 million people will have the disease. Regular, comprehensive eye exams can detect the early signs of AMD. Though any vision that is lost to the disease cannot be restored, there are treatments that can slow AMD's progress.

About Our Age-related Macular Degeneration Report

We analyze 3 SNPs associated with Age-related Macular Degeneration: rs1061147, rs547154, and rs3750847. Based on these markers, our estimate of a person's lifetime odds of getting Age-related Macular Degeneration can range from 1% to 33%. Our estimate is applicable to people of European ethnicity, based on available published scientific research.

 

 

 

Bookmarks The following information, which has been distilled by the casebook author from this and other websites is particularly relevant to this casebook.
Bookmarks - Web
Web Page Notes Concepts
 Macular degeneration - Glossary Entry - Genetics Home Reference Genetics Home Reference at National Library of Medicine (Macular degeneration)
 
 http://www.clinicaltrials.gov/ct2/results?term=macular degeneration 515 clinical research trials (Macular degeneration)
 

This web-site is for informational purposes only and is not intended as a substitute for advice from your doctor. It should not to be used for self-diagnosis or treatment.