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
Click
Here For Abstract
Anna Sophia McKenney