Doctors test gene therapy to treat blindness

By Ben Hirschler

LONDON (Reuters) - A team of doctors has carried out the world's first eye operations using gene therapy to try to cure a serious sight disorder, officials said on Tuesday.

The group from Moorfields Eye Hospital and University College London (UCL) has operated on a small number of young adults with Leber's congenital amaurosis, a type of inherited childhood blindness caused by a single abnormal gene.

The condition prevents the retina from detecting light properly, resulting in progressive deterioration and severely impaired eyesight. There is no effective treatment.

The new experimental procedure involves 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 a harmless virus or vector.

The doctors are working alongside Seattle, Washington-based biotech firm Targeted Genetics Corp., which made the vector being used in the Phase I/II trial.

It will be several months before the success of the procedure can be properly assessed but medics said there had been no complications so far.

The move into human testing follows 15 years of laboratory and animal experimentation, including tests on dogs whose vision was restored to the extent they could navigate a maze with ease.

"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," Robin Ali, professor of human molecular genetics at UCL, said in a statement.