Genetic Cure In Sight

An ongoing clinical trial of gene therapy for an inherited form of impaired vision has released positive initial results. The trial, conducted by the UCL Institute of Ophthalmology and the NIHR Biomedical Research Centre, shows thus far “that the experimental treatment is safe and can improve sight” in victims of Leber’s congenital amaurosis (Metcalfe et al, 2008). Leber’s congenital amaurosis (LCA) is an inherited condition caused by a mutation in several genes, including RPE65. It impairs vision from birth and progressively deteriorates eyesight until blindness, typically when the victim is in their thirties. Currently there is no effective treatment. The trial involved injecting a vector containing the normal coding sequence of RPE65 into the retinae of three young adults (aged 17-23) suffering from LCA. In such a trial, the two major aims were to assess the safety of the procedure and the effectiveness of the gene therapy.

After the treatment, all three patients were examined for possibly adverse reactions to gene therapy; fortunately, none were identified. Two of the patients possessed similar degrees of eyesight to what they had prior to the treatment, whereas the other patient showed improved eyesight in several areas, including night vision, dark-adapted perimetry and microperimetry. The researchers involved believe this patient's improvement was due to the fact that his condition was not as far developed as the other two patients. This suggests that early detection may be the key strategy in future treatment and prevention of blindness. Despite the change occurring in only one out of the three cases, the eyesight all three patients are still subject to improvement within the next few years.

Professor Ali, the trial’s team leader, emphasised that although “gene therapy is still an experimental treatment... these results give us great confidence that this technique is safe and can bring real benefit to patients with impaired vision” (as quoted by Metcalfe, 2008). With further advances in technology and our understanding of genetics, it is hoped that similar procedures can lead to treatment of a broader range of conditions.

References:

Bainbridge et al, 2008, Effect of Gene Therapy on Visual Function in Leber's Congenital Amaurosis, New England Journal of Medicine.

Metcalfe et al, 2008, Results of world's first gene therapy for inherited blindness show sight improvement, UCL Institute of Ophthalmology.

http://content.nejm.org/cgi/content/full/NEJMoa0802268

http://www.ucl.ac.uk/media/library/Genetherapyblind

http://www.reuters.com/article/scienceNews/idUSL016653620070501?pageNumber=1

http://content.nejm.org/content/vol358/issue21/images/large/06f2.jpeg

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