Sunday, September 19, 2010

Shortsighted

I found this great story through work about nearsightedness and so went on to the American Optometric Association's website to get a little bit more info first.

Nearsightedness is medically termed myopia. It is a vision condition where close objects appear clear but far away objects look blurred. Anatomically, the eyeball is too long or the cornea has too much curvature. Regardless of which one it is the extra length of the eye means that light isn't focused correctly onto the retina. As a condition, myopia is actually pretty common, affecting nearly 30% of the U.S. population. Usually, it first exhibits itself in school-age children, and as the eye grows during childhood until age 20 the condition progresses. Eyeglasses or contact lenses are prescribed to correct nearsighted by bending the incoming light to the eyes. Another option is orthokeratology, or corneal refractive therapy, a non-surgical procedure where a person wears a series of specially designed rigid contact lenses to gradually reshape the curvature of the cornea. Yet another option is laser procedures that reshape the cornea by removing a small amount of eye tissue with a highly focused laser beam.

If you scroll through the advanced online publication of Nature Genetics you will notice an article about the myopia gene. The study conducted a genome-wide association study for refractive error in 4,270 individuals. Basically, they were looking for the gene that causes nearsightedness. The researchers identified SNPs (single nucleotide polymorphisms which occur when a single nucleotide in the genome differs between members of a species or individuals) on 15q25 associated with refractive error. So they replicated the association in six adult cohorts of European ancestry with a total of 13,414 individuals. Actually, these 'individuals' numbers are twins. They found that the locus overlapped a transcription initiation site called RASGRF1. This particular gene is highly expressed in neurons and in the retina and as such is crucial to retinal function and visual memory. Additionally, the scientists found that found a different gene, called CTNDD2, is related to myopia in Chinese and Japanese populations. To be thorough, the researchers also created mice that were missing the gene. These mice showed changes in their eye lenses, adding further evidence to the findings.

Check out the paper:
Hysi, Pirro G., et al. (2010) A genome-wide association study for myopia and refractive error identifies a susceptibility locus at 15q25. Nature Genetics: published online (DOI: 10.1038/ng.664)

Here's a report through Duke Medicine (one of the teams on the paper):
http://www.dukehealth.org/health_library/news/gene_discovery_could_yield_treatments_for_nearsightedness?utm_source=dukehealth.org&utm_medium=rss&utm_campaign=RSS_news

The Australians were also on the team, read an article from there here:
http://www.abc.net.au/science/articles/2010/09/13/3009820.htm

(image from healthtree.com)
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