By Fergus Walsh
Medical correspondent, BBC News
A gene therapy trial for the fatal disorder Duchenne muscular dystrophy (DMD) is about to begin in London.
Daniel is taking part in the trial
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.
HOW THERAPY WORKS
A single faulty gene on the x-chromosome causes Duchenne Muscular Dystrophy
There are some small errors in the genetic code on the gene which means that it is unable to produce the dystrophin protein which keeps muscles strong.
The treatment involves scientists making a very small piece of genetic material - a molecular patch which once inside the muscle cell, binds to the piece of code which surrounds the genetic error
This enables the gene to produce a working version of the dystrophin gene. It's been tested successfully in mice but these will be the first tests in humans
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.
Daniel has high hopes for the future
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 Duchenne."
The Muscular Dystrophy Campaign said it had high hopes the outcome of the study would be positive.
Dr Marita Pohlschmidt, the campaign's director of research, said: "The start of the trial is exciting news because it will provide us with the evidence of how this promising technology will prevent the wasting of muscles in boys with Duchenne muscular dystrophy.
"This is the first time that results from this type of research are so close to being translated into a treatment.
"We are proud that we were able to play a vital role in the formation of the scientific consortium and to support the preclinical work with more than £500,000."