Humans who have had their DNA genetically modified could exist within two years after a private biotech company announced plans to start the first trials into a ground-breaking new technique.

Editas Medicine, which is based in the US, said it plans to become the first lab in the world to 'genetically edit' the DNA of patients suffering from a genetic condition – in this case the blinding disorder 'leber congenital amaurosis'.

The disorder prevents normal function of the retina; the light-sensitive layer of cells at the back of the eye. It appears at birth or in the first months of life and eventually sufferers can go completely blind.