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AT LAST there is hope for sufferers of the fatal disease muscular dystrophy.
Researchers in the US have managed to treat the disease in mice using gene
therapy鈥攅ven though the gene needed is an absolute whopper.

Children with severe Duchenne muscular dystrophy suffer from progressive
muscle wasting. They are usually confined to a wheelchair in their teens and die
in their early twenties. Until now, gene therapy has been impossible because the
gene that needs to be replaced is the largest ever found鈥攐ver 3 million
base pairs long. The viruses usually used to deliver genes to cells only have
enough space for a gene a thousandth of the size.

However, some people have only mild symptoms, even though they are missing
large parts of the gene. So Bing Wang and colleagues at the University of
Pittsburgh created 鈥渕ini-genes鈥� a thousand times smaller than the normal gene,
containing only the essential parts.

The mini-genes fit snugly inside a so-called adeno-associated virus.
Injecting the virus into the muscles of mice with severe muscular dystrophy
stopped and even reversed the disease鈥檚 progression.

Steven Hart of the Institute of Child Health in London thinks mini-genes are
a good short-term solution. 鈥淏ut in the long run we鈥檒l want to deliver ways of
regulating gene expression too, and synthetic vectors with more space will be
needed,鈥� he says.