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New Gene Treatment Trial For Blindness

October 28, 2011

A pioneering new treatment that uses DNA to correct a hereditary and incurable form of blindness has been performed for the first time in a British hospital.

The landmark procedure is aimed at stopping the progression of a genetic disorder which sets in during childhood and slowly leads to total blindness.

It marks the first attempt by scientists to combat the effects of choroideraemia, a condition caused by a missing gene in the light-sensitive cells at the back of the eye.

Oxford University researchers carried out the trial on Jonathan Wyatt, an arbitration lawyer from Bristol, at Oxford Eye Hospital on Monday.

Mr Wyatt, the first of 12 patients selected for the test procedure, began losing his sight at the age of 19 and was later forced to give up his job because he could no longer read clearly.

At the age of 63 Mr Wyatt still has a limited amount of sight but the condition – which affects about 1,500 people in Britain – often leads to blindness by the 40s.

In a bid to preserve his remaining sight, doctors injected ten billion copies of the missing gene, called REP 1, directly into his left eye while leaving the right untreated as a “control”.

Lacking the gene causes the cells at the back of the eye which collect light to break down and die, causing sufferers to begin losing their sight before the age of 10 and develop “tunnel vision” by their late teens.

By inserting copies of the gene into an empty virus particle, which was programmed to move towards the affected cells, known as photoreceptors, scientists hope they will have activated the gene and prevent any further harm.

Researchers expect to know if the treatment has worked within the next two years, and will treat Mr Wyatt’s other eye if the results are positive.

Doctors hope that, if successful, the technique could lead to new treatments for a wide range of previously incurable genetic eye conditions including macular degeneration, the most common cause of blindness in the elderly.

Professor Robert MacLaren, who led the trial, said: “If this works with Jonathan then we would want to go in and treat patients at a much earlier stage in childhood, effectively where they still have normal vision and can do normal things to prevent them from losing sight.

“The photoreceptors have always been the final frontier for gene therapy in the eye.

“I cannot describe the excitement in thinking that we have designed a genetic treatment that could potentially stop [the disease] in its tracks with one single injection.”

The one-off treatment, which should last for life, is not aimed at reversing the deterioration that has already taken place but Mr Wyatt said last night he believed his vision had begun to improve.

He said: “There is, I think, a possibility that it will improve the sight of the eye.

“For instance today I looked at my wife’s mobile phone and was able to identify all the digital letters – I gave her my mobile phone with small digital letters four years ago because I could not read it any more.

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