DNA 'patch' therapy skips gene defects

British-based scientists have developed a new treatment for genetic defects, which could help thousands of people suffering from a muscle-wasting disease that kills them by the age of 30.

The therapy, so far tested in mice, could be tried out on volunteers with Duchenne muscular dystrophy, a genetic disease which rapidly erodes muscular strength, within a few years, suggested Professor Terrence Partridge, who with Dr Qi Long Lu at the Medical Research Council's Clinical Sciences Centre has developed the new approach.

"Most people with muscular dystrophy have a fault in the middle of the gene which prevents it from making the correct protein," said Professor Partridge.

"We have used 'antisense' therapy, which effectively skips over the faulty piece of the gene. Most DMD patients have a defect in the middle of the gene that you can get rid of without a loss of function."

Antisense therapy injects drugs with small pieces of genetic code that trick the cell's gene-translating machinery into jumping past a particular piece of DNA. By omitting the faulty part of the DNA, the gene's normal function can be mostly restored.

DMD is caused by a genetic defect in the X chromosome, and causes failure of the muscles to make dystrophin, a protein that stops them from wasting. Between 50 and 100 babies, mostly boys, are born with the disease every year. They usually die from respiratory or heart failure between the ages of 20 and 30.

Other researchers have tried gene therapy techniques with the aim of replacing the faulty genes. Those however demand the use of potentially virulent viruses to deliver the genetic material. The MRC team, whose work is published today in the journal Nature Medicine, believes the antisense method offers a safer route, because it is highly specific to the dystrophin gene.