For the first time in history, doctors have a chance to help patients with Leber's hereditary optic neuropathy, a condition that leaves young people blind in a matter of weeks. This disease is caused by mutations in the cells of the neurons of the eye and therefore cannot be cured with drugs. Scientists from the University of Cambridge, the University of Pittsburgh and the Paris Institute of Vision decided to follow the principle of "knock out like a wedge" and defeat one mutation with another.
Leber's neuropathy affects people in their 20s and 30s, an average of 1 in 30, 000. It all starts with a malfunction in the MT-ND4 gene, due to which the retinal ganglion cells are degraded and destroyed. These are neurons in the eye, on which the process of transmitting information to the brain depends, therefore, as they die, the optic nerve is also damaged. When this happens, blindness is almost guaranteed, with less than 20% chance of healing naturally.
Scientists have collected a fragment of rAAV2 / 2-ND4 DNA, modified to replace the mutated fragment in the MT-ND4 gene with a normal, original one. The viral vector was injected into the vitreous humor at the back of the eye. The study involved 37 patients who had become blind 6-12 months earlier, and as a result, 78% of them showed a clear improvement in visual function.
Most of all, scientists were struck by the fact that injections were made in one eye, and recovery was observed in the second eye too. Testing on macaques, whose vision system is similar to the human, showed the incredible - the embedded DNA fragment in an unknown way moved from one eye to the other. At the same time, it also multiplied, because it was found in different parts of the eye, which made scientists talk about "interocular diffusion." It is obvious that the body reacts to directed mutations, but the very mechanism of this reaction has yet to be studied.