Gene therapy used in attempt to halt blindness

A British man has become the first person to receive an advanced gene therapy treatment in a bid to save his sight. Jonathan Wyatt, aged 63, is the first of 12 patients to have the experimental procedure to try and halt the progression of his genetic eye disorder, choroideraemia. While he still has some sight, if left untreated, he would eventually become blind.

If successful, the treatment may soon be in widespread use, and potentially modified to treat other causes of blindness, such as age-related macular degeneration, which affects over 300,000 people in the UK.

Professor Robert MacLaren from the University of Oxford, who is leading the trial, said: 'This disease has been recognised as an incurable form of blindness since it was first described over 100 years ago. I cannot describe the excitement in thinking we have designed a genetic treatment that could potentially stop it in its tracks with one single injection'.

In choroideraemia, eye cells responsible for sensing light — called photoreceptor cells — slowly die off. Vision first becomes affected during childhood and deteriorates over time, eventually leading to complete blindness. The hereditary condition, which affects 1,500 people in the UK, is hereditary and occurs when patients lack a functioning copy of the REP1 gene.

The procedure involves injecting ten billion functioning copies of the REP1 gene directly into the photoreceptor cells in the back of the eye. It is the first time these specific cells have been targeted for gene therapy.

It is hoped the treatment will prevent vision from getting any worse, though it is not expected to reverse damage already done. Professor MacLaren therefore believes that the earlier the therapy is administered the better.

'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', he said.

Professor Sir John Bell, president of the Academy of Medical Sciences, said: 'There is the possibility that you could actually correct the gene defect. Of all the things that are available for this particular set of diseases this is by far the most exciting'.