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Genetic Predisposition Test for Macular Degeneration

Overview of Macular degeneration: Age related macular degeneration (AMD) is an age-dependent cause of legal blindness (visual acuity of 20/200 or worse) and one of the highly reported cases across the world. Management of AMD is a challenge as it is considered as non-curable; however few clinical cases can be treated with laser-photocoagulation. As the overall life-expectancy of the world increases, so does the prevalence of AMD.

About Macular Degeneration

Understanding Macular degeneration: Macula is the portion of the eye that is responsible for detailed vision as well as colour vision. AMD leads to degeneration of the macular cells. There are two types of macular degeneration:

Dry (atrophic) form: This is associated with the breakdown of the cells of macula, thereby affecting the central vision.
Wet (exudative) form: In this form of macular degeneration, abnormal blood vessels develop under the centre of the retina, which sometimes leaks and leads to distortion of vision. Hence, compared to dry form, wet form is considered as a more serious condition.

Determining the risk groups

Age: With age, chances of developing AMD increase

Sometimes colour matter: The risk of the development of AMD is high among Caucasians (white race).In fact, people with lightly coloured iris are at a higher risk in developing age-related macular degeneration than those with a black or brown iris

Gender bias: Women are more susceptible to developing AMD than men. Higher life-expectancy among females is believed to be the reason for this difference

Some genes responsible for AMD

  • ABCA4
  • APOE
  • ARMS2/LOC387715
  • HTRA1
  • C2/CFB
  • C3

Eye on Smoke and also Genetics: Smoking is a modifiable factor that increases the chances twice as much of development of AMD.

Heredity is a non-modifiable factor that causes AMD. As high as 10-20% of the cases with AMD have at least one first-degree family member with vision loss. Several genes have been identified after years of research (Table1). As shown in the table, multiple genes are responsible for the pathogenesis of AMD. Results from these studies have established that the gene that codes for the apolipoprotein E (APOE) is related with pathogenesis of AMD. The risk of AMD increases due to ɛ2 allele; however ɛ4 allele has shown to have protective effect. In 2006, a study from Columbia University Medical Centre revealed the two genes-Factor H and Factor B has significant role in the pathogenesis of AMD. 74% of patients with these genes or their variant eventually develop AMD. Factor H gene helps to code the proteins that help fight inflammation post bacterial or viral infection.

Prevention is better than cure: Ocular morbidity associated with AMD is almost certain. Preventive measures can help safeguard high-risk patients. Measures that can prevent development of AMD are as follows:

  • Patient education- Making patients aware of AMD
  • Lifestyle changes- Right body mass index (BMI) giving up smoking can prevent AMD in high risk persons
  • Careful evaluation
  • Long-term surveillance
  • Nutrition: Nutrients such as lutein/zeaxanthin, vitamin C, vitamin E, and zinc have shown to prevent AMD