Scientists believe gene therapy could be used to slow down or prevent the fatal brain disorder Huntington's disease.
Huntington's is a fatal brain disorder
Researchers in the United States say tests on mice have shown the treatment could be effective in humans, according to a report in New Scientist magazine.
Gene therapy is a way of treating disease by either replacing damaged or abnormal genes with normal ones or by providing new genetic instructions to help fight disease.
Instead of giving patients drugs to treat or control the symptoms of the disorder, doctors attempt to correct the underlying problem by introducing healthy copies of damaged or missing genes into some of the patient's cells.
The treatment is controversial not least because there has been little evidence until recently that it works. It has been shown to work in animals but there has been only limited success in humans.
But Dr Beverly Davidson and colleagues at the University of Iowa say they believe the treatment could help people with Huntington's disease.
Huntington's is an incurable genetic disorder in which nerve cells in the brain are damaged, causing physical, mental and emotional changes. It usually starts when people are aged between 30 and 50.
It is caused by a genetic mutation which inserts a repeated DNA sequence into the gene encoding the Huntington protein. It is believed that this damages cells by interfering with their energy-producing mechanism or mitochondria.
The US researchers have been able to shut off or silence this gene in mice using gene therapy.
Completely silencing the gene in people with the disease is not an option because brain cells may not survive without the protein.
However, people have two copies of most genes and usually only one is defective in Huntington's disease.
The scientists are confident that even where both genes are faulty they will be able to silence both and insert a new healthy gene.
In addition, they have carried out tests on a similar disease using human cells and have found that the technique can help to reduce expression of the defective protein.
In the case of Huntington's this could help to slow down the progress of the disease and reduce symptoms.
"If you reduce levels of the toxic protein even modestly, we believe you'll have a significant impact," said Dr Davidson.
Further research is needed before her team starts work on Huntington's using human cells.
Extensive studies will be needed before the technique could be tried in live patients.