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Duchenne muscular dystrophy is the most severe form of muscular dystrophy. It affects about one in every 3500 boys who are born – about 100 boys a year.
It is a sex-linked genetic condition which means the boys cannot make a protein called dystrophin, a protein which is vitally important for maintaining healthy muscles. Without it the muscles weaken and waste away, so that by their early teens most affected boys are confined to a wheelchair and their life expectancy is only 20-30 years.
Muscle fibres have been replaced by fat cells in patients with muscular dystrophy
The faulty gene is very large, which makes normal gene therapy techniques difficult. However researchers in the United States and in Britain have found ways of using parts of a healthy gene, called mini-genes, to repair the damaged DNA, enabling the muscles to produce dystrophin and to function in a much more normal way. What is more, the effect has been long term – the protein was still being made a year after the gene was inserted. Another successful treatment in mice has been to use RNA molecular patches - which patch up, or mend, the mutation in the body. The only problem is that the gene therapy technique has so far only been used sucessfully long term in mice and golden retrievers, which have a natural mutation similar to muscular dystrophy.
However since 2007 there have been small trials of molecular patches in human volunteers. Gene therapy has not yet been fully successful in overcoming any genetic diseases, so the patients who are taking part in these early trials of a possible new treatment – and their parents – are very brave. So far the molecular patches have not caused any side effects - and although numbers in the trial are tiny, some of the boys have started to make dystrophin in their muscles.