Can retinitis pigmentosa be cured?

Kat - And now it's time for our monthly question. Listener Joe Devin asks, "Some years ago, it was announced in the news that someone had been cured or partially cured of Retinitis pigmentosa using gene therapy in a US laboratory, but I have never heard any follow-up to this announcement, and it seems that nothing has ever come of the stem-cell technique that was used. What has been going on in this field of research, and is there any concrete hope for a cure for the disease?" To find some answers, I spoke to Professor James Bainbridge, professor of retinal studies at University College London and consultant at Moorfields Eye Hospital.

James - There's been a lot of progress in this area over the last few years and we and others have shown that in a certain condition, it does seem to be possible to actually improve aspects of sight by providing people with normal copies of the genes that they otherwise lack.

Kat - Particularly in the case of retinitis pigmentosa, where are we with gene therapy for that particular disease?

James - So, retinitis pigmentosa is a term that describes a degeneration of the retina typically because of an inherited defect, inherited disorder. This particular term refers to many hundreds of different conditions, all of which depend on a specific gene. We are excited because there is increasing evidence that for at least one form of that condition associated with defects in one particular gene, provision of a normal gene through gene therapy does appear to confer some significant benefit. The challenge now is to try to find out how that can be extrapolated, if you like, how that technology can be used to provide a similar level of benefit or perhaps even more robust and more durable level of benefit for people who have different forms of a similar condition.

Kat - Do you think that this gene therapy approach is a hope for a cure in the future?

James - Absolutely. I think that we're very confident that this technology will offer some benefit for people with specific forms of inherited retinal disease. We don't know yet the extent to which people might benefit or for how long, and we don't know whether this particular treatment can prevent people from losing sight altogether. But it would be fantastic to think that it could protect them by slowing degeneration and perhaps protecting their sight for longer than they can otherwise expect.

Kat - What kind of timescale are we looking at?

James - So, a lot of this work has been done in the laboratory using models of these conditions. But we're very excited that we are already well into the stage where these technologies are being used in people with blinding disorders. So, there are a number of clinical trials now involving people poor sight who are already benefiting from this technology. At the moment, the people who have been included have - and it's important to emphasise this - very specific forms of the condition because we only have tools to intervene in a very limited number of these conditions. But we hope in the future, that we might be able to expand the portfolio of treatments so that more people can benefit.

Kat - Thanks to Professor James Bainbridge for that answer. And if you've got any questions about genes, DNA and genetics, just email them to me at genetics@thenakedscientists.com.