Macular Degeneration Could Be Affected By Genetic Variant

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Main Category: Eye Health / Blindness
Also Included In: Genetics;  Seniors / Aging;  Immune System / Vaccines
Article Date: 11 Mar 2008 - 0:00 PDT

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Genetic variations that affect the production of various chemicals in the inflammation pathways could provide more information about age related macular degeneration (AMD), according to research released in the British Journal of Ophthalmology on February 28, 2008.

AMD is a progressive eye diseases which affects the center of the retina, known as the macula, at the back of the eye. This portion of the eye is most specialized for fine, central vision tasks, including reading or driving. It is most common among the elderly, and in developed countries it is a major cause of untreatable blindness.

Researchers from the University of Southampton in the UK investigated genes controlling the production and suppression of cytokines, which play an important role in the inflammatory response. They focused on four specific genetic variations, each related to control of expression of certain cytokines.

To this end, they examined DNA samples from people aged 55 or older. 478 were people presenting with AMD and 555 people showed no signs of the disease. One of the genetic variants examined (251A/T) is associated with the gene boosting production of interleukin 8 (IL-8). In previous studies, this genetic variation has been linked to several inflammatory diseases and cancer, and this genetic variant was significantly more prevalent in patients with AMD. The results remained conclusive after normalization for age, sex, weight, and smoking, all of which can specify a higher risk of AMD.

The authors indicate that, in a larger study, their findings could help create a test to screen for AMD genetically, as well as potential directions for development of drugs to control it.

In an editorial accompanying the article, opthamology specialists from the National Institutes of Heath and the University of Michigan cautiously commend the results. They note that many further studies are necessary before any direct causal relationship can be confirmed. However, they claim that the explanation is plausible, because the development of AMD has been linked to cooperative effects from genetic and environmental factors. That is, natural changes that come with aging, such as the accumulation of oxidative stress, seem to initially give rise to the disease, which becomes worse with additional immune system activity.

Interleukin 8 promoter polymorphism -251A/T is a risk factor for age related macular degeneration
Srini V Goverdhan, Sarah Ennis, S R Hannan, K C Madhusudhana, A J Cree, A J Luff and Andrew J Lotery
Online First Br J Ophthalmol 2008
doi: 10.1136/bjo.2007.123190
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Written by Anna Sophia McKenney
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