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Last Updated: Sunday, 7 May 2006, 23:10 GMT 00:10 UK
Self-repair gene therapy promise
Gene analysis
Gene therapy experts say they have found a way to persuade cells to repair themselves.

Instead of replacing a faulty gene, the new approach harnesses the cells' own correctional mechanisms.

German researchers showed a drug could influence the way a gene behaved in patients with a debilitating genetic condition.

Details of the research are being presented to the European Society of Human Genetics conference in Amsterdam.

This work shows that it may be possible to stimulate a related gene, and reduce the symptoms of the disease
Dr Fred Kavalier, British Society of Human Genetics

The research focussed on spinal muscular atrophy (SMA), a relatively common inherited disease, and the leading cause of death in infants, affecting about one in every 6,000 newborns.

Due to degeneration of the motor neurons in the spinal cord patients develop muscle weakness and atrophy of the legs, arms and trunk.

In patients with SMA the survival motor neuron gene (SMN1) is deleted, but they all carry a copy gene (SMN2).

However, this only produces about 10% of the correct protein which is insufficient to prevent the diseases.

The severity of the SMA is influenced by the number of SMN2 genes, which normally vary between one and four - the more copies there are the better the patient fares.

Protein levels boost

The researchers, from the Institute of Genetics at the University of Cologne investigated a drug called valproate, which is already used to treat epilepsy.

Lab tests had shown it could increase levels of the SMN protein by up to four times.

Valproate was also found to raise SMN levels in brain tissue.

The team first treated 10 parents of children with SMA with valproate for four months.

It was found that using the drug significantly increased SMN levels in blood.

Following this, 20 SMA patients were treated with valproate.

Seven showed increased SMN2 levels in their blood.

'A small step'

However, it remains unclear whether SMN expression in blood reflects SMN expression in motor neurons, and would therefore have an effect on muscle strength.

But the researchers said they hoped their findings could have significant benefits in the future.

Professor Brunhilde Wirth said: "The long-term outcome could be both improved therapy to enable a better quality of life for SMA patients, and also the introduction of neonatal screening so that therapy could be started before the first symptoms appear."

Dr Fred Kavalier, of the British Society of Human Genetics, said: "This work shows that it may be possible to influence the behaviour of genes with drugs.

"This is not a cure for SMA, but it's a small step along the road that may lead to an effective treatment.

"It is exciting to discover that a drug that is used to treat epilepsy may also be helpful in a completely different condition."

Professor Robin Lovell-Badge, head of genetics at the Medical Research Council's National Institute for Medical Research, said it was crucial to obtain detailed basic understanding of specific genes, and the nature of the defects responsible for genetic disease before the knowledge was applied to treating patients.

He added: "It is still too early to say whether or how well these particular approaches will work in the clinic,.

"But the preliminary results are encouraging and the knowledge gained will hopefully generate yet further tricks to bypass the unlucky set of cards that some people are dealt."

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