After the injection of healthy copies of a gene in their retina, four children with a serious and progressive form of blindness have returned to see.
An experimental form of gene therapy has restored most of the sight in four children with a form of retina dystrophynow capable of perceiving only lights and shadows. It is the first time that the disease, one of the most serious causes of blindness in pediatric age, can be partially treated: the encouraging results have been described in an article in the magazine Lancet.
Alteration of the retina. The small study participants are affected by Leber amaurosis of Leber (LCA)a hereditary retinal dystrophy: it is a rare disease of the retina, the part of the eye that transforms the bright stimuli into nervous signals, characterized by the degeneration and the progressive loss of retinal photoreceptors (cones and sticks).
This disease begins in the first six months of life and affects 3 children per 100,000 living born. Represents 10-18% of all congenital retinal dystrophies and entails a serious visual deficit from the first year of lifeso much so that all four study participants were legally recognized as blind.
A virus like taxi. The trial was followed by the scientists of the Institute of Ophthalmology of the University College London. The four patients, who were one or two years of age and came from the United States, Türkiye and Tunisia, were operated in 2020 at the Great Ormond Street Hospital in London. The intervention, in laparoscopy and lasting one hour, consists in the‘Inject healthy copies of one of the genes which can be responsible for this disease, in this case the Aipl1, in the retina of patients.
The healthy gene, fundamental for the correct function of the photocercers, that is, of the cells sensitive to light in the retina, was transported in the eye through a viral carrierthat is, a virus made harmless can release genetic material in a cell. Once on site, the functioning genes helped the photocercers to work better and survive longer.
A rebirth. To minimize damage in case of side effects, the intervention concerned only one eye by patient. But the results were remarkable: starting from the first month after the operation the children started to respond actively, even with signs of annoyance, in the presence of light in the room. Today, four years later, they manage to distinguish games at a distance that they would once not have noticed a few centimeters from the nose, and in some cases even writing and drawing.
As predictable, the vision in the untreated eye has instead deteriorated.
Hurry. Now the London team intends to monitor young patients to understand how long the effects of therapy will last: it is possible that later they need new interventions of this type, but they have the advantage of having started correcting the visual deficit at an early age. Intervening as soon as possible is of vital importancebecause hypovision in such small children can have serious consequences on cognitive development. From 2020 to today, seven other children have been treated with the same therapy at the Evelina London Children’s Hospital.
