Officials have announced the completion of the world's first eye operation using gene therapy. A team of British doctors from Moorfields Eye Hospital and University College London (UCL) carried out the operations in an attempt to cure a serious sight disorder- Leber's Congenital Amaurosis or LCA.
The group operated on 12 young adults with LCA, a type of inherited childhood blindness caused by a single abnormal gene.
AdvertisementLeber's Congenital Amaurosis is not a single specific disorder. It is the term used for a group of conditions that have in common, abnormality of retinal receptors, which result in severe vision impairment from birth.
Within the LCA group, genetic testing can now in some cases, identify which of more than six distinct genes has an error, but as yet this does not alter management. However gene therapy, with the goal of at least stabilizing any residual vision, may be a possibility in the not too distant future for the small number of children with the RPE65 genotype.
The condition prevents the retina from detecting light properly, resulting in progressive deterioration and severely impaired eyesight. There is no effective treatment as of now.
The new experimental procedure involved inserting normal copies of the faulty RPE65 gene into cells of the retina -the light-sensitive layer of cells at the back of the eye - using as a vehicle like a harmless virus or vector.
The doctors operated first on Robert Johnson, a UK man born with a sight disorder which means he can see very little at night, and which deteriorates with age. Yet, it will be several months before the researchers know whether their work has been a success.
The British doctors are working alongside Seattle, Washington-based biotech firm Targeted Genetics Corp., which made the vector being used in the Phase I/II trial.
This move into human testing follows 15 years of laboratory and animal experimentation, including tests on dogs with LCA, whose vision was restored to the extent they could navigate a maze with ease.
Said Robin Ali, professor of human molecular genetics at UCL: "Testing it for the first time in patients is very important and exciting and represents a huge step towards establishing gene therapy for the treatment of many different eye conditions."
The clinical trial was given a million pounds ($2 million) of funding by Britain's Department of Health, which said the pioneering research underlined the country's leading position in gene therapy in Europe. The idea of using gene therapy to fix diseases caused by genetic faults has long appealed to scientists, although getting the idea to work in practice has proved the tricky part.
Some gene therapy approaches have helped patients. But one 18-year-old volunteer died in a gene therapy experiment in 1999 and two French boys cured of rare immune disease later developed leukemia. Over 70 percent of gene therapy trials to date have been for cancer, where the process is complicated by the need to reach multiple sites in the body.
In contrast, the eye is relatively straightforward according to Andrew George of London's Imperial College. "The eye is good for gene therapy because it is a simple organ and it is easy to see what is going on. There is hope that once gene therapy is developed in the eye, scientists could move on to more complex organs," he was quoted.
Some indications of the result may be available within several months. However, the subjects - Mr. Johnson and the 11 others - will need to be followed up to assess the long term effect of the treatment. It is anticipated that the best results will be achieved in younger patients, as they will be treated when the disease is in its earlier stages of development.
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