Washington: Scientists have found a gene
responsible for myopia or nearsightedness, a discovery that
could lead to new treatment for the eye disorder which is
at present affecting a quarter of the world`s population.
Myopia happens when the focal point of an image falls
just short of the retina at the rear of the eye, causing
blurred distance vision. It`s the most common eye disorder in
the world but little is known about its genetic underpinnings.
Now, a team of scientists led by researchers at Duke
University Medical Centre in Durham claimed that they have
uncovered a gene, identified as RASGRF1, which triggers the
vison problem.
"Because RASGRF1 is highly expressed in neurons and the
retina, it is crucial to retinal function and visual memory
consolidation," said lead author Terri Young, a researcher in
the Centre for Human Genetics at Duke.
Young and his team found several distinct spellings of
DNA code near the RASGRF1 gene that had a strong association
with focusing errors in vision in Caucasian people from
several different regions, including Dutch, British and
Australian subjects.
These findings were validated in six other Caucasian
adult groups in a total of 13,414 subjects.
When the scientists created mice that were missing the
correct gene, these mice showed changes in their eye lenses.
"This was biologically convincing," Young said. "The
RASGRF1 provides a novel molecular mechanism to study so that
we can work to prevent the most common cause of visual
impairment."
He said: "The eye is already an organ of choice for gene
therapy, for example, because the eye`s small volume and
self-contained area allow the therapy to remain inside the eye
in a concentrated volume.
"In addition, the eye`s accessibility lets clinicians
observe the effects of treatment over time with noninvasive
methods that can illuminate and test the retina and other eye
structures."
Often the discovery of a gene still means that many years
could pass before a treatment becomes available. However, gene
therapies are already working well in some eye conditions, and
myopia may be a good candidate condition for gene repair.
While many cases of myopia are mild, about two to three
per cent are pathological cases with retinal detachment,
premature glaucoma, macular bleeding, and glaucoma leading
eventually to blindness, said Young, who has spent over a
decade studying the severe form of myopia.
Up to 80 per cent of people in Singapore have myopia while
about one in three Americans is suffering from the disease.
Countries with a high prevalence of nearsightedness have a
hard time finding fighter pilots, to give one example of how
myopia affects a population.
The exact cause of nearsightedness is unknown, but two
factors may be primarily responsible for its development:
heredity and visual stress.
"Today`s near work forces our eyes to constantly be in
tension to focus on near objects -- reading papers and
watching monitors... These factors affect children with
developing vision, as well as many adults," said Young.
The study was published in the journal Nature Genetics.
PTI
