A gene therapy trial for the fatal disorder Duchene muscular dystrophy (DMD) is about to begin in London.
In a world first, a small group of patients will be injected with an experimental drug which it is hoped will extend their lives.
DMD, which affects boys, is caused by a single faulty gene, and results in progressive muscle wasting.
The injection contains a "molecular patch" targeting the faulty gene so that it should work again.
At first, minute quantities of the drug will be used - to check it is safe.
If it works the drug will effectively knit together the key damaged section of DNA, allowing it to begin producing a protein that keeps the muscles strong.
The hope is it could slow, or even halt the progression of muscle wasting, and give some patients the chance of living into old age.
Animal trials of the drug have proved highly successful.
If it works in humans, patients would need regular infusions of the drug.
Lead researcher Professor Francesco Muntoni, of Imperial College London, has high hopes.
He said: "It will be truly life changing, and life extending for these people. "Maybe this will not be a complete cure, but it could definitely buy a lot of time for these children." Professor Muntoni describes the gene therapy as like a piece of molecular velcro which will form a temporary repair.
Gene therapy will work best in young children, as it cannot reverse existing muscle damage.
Daniel Emerson-Smith used to be able to run around and kick a football, but DMD is gradually destroying all the strength in his body.
He is just 16 and now needs a wheelchair to get around. People with DMD rarely live beyond their 20s.
But Daniel is hopeful that taking part in the trial will transform his prospects.
He said: "I think it will help me live longer, and slow down the illness a bit.
"I will be able to move around a bit more, and have some independence, and maybe take my Mum out."
Nick Caitlin, of the charity Parent Project UK, which has partly funded the trial, said: "This is a real red letter day for all the parents who have campaigned tirelessly over the last couple of years to get funding for treatments or a cure for Duchene." ( BBC )