Name: Macular Degeneration
Description: Sample casebook 05
This casebook is published and has been read 458 times.
The author of this casebook has identified the following medical topics as being highly relevant to this casebook.
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.
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.
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.
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.
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.
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.
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:
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.
You can find out more information about AMD by talking with your doctor and visiting these Web sites:
Age-related Macular Degeneration is one of the conditions that 23andMe analyzes. Our service includes the following information:
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.
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.
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