Huntington's disease
Brain scan of a patient with Huntington's disease. Frank Gaillard

Scientists have announced that the genetic mutation which causes Huntington's disease - a deadly neurodegenerative disorder - has been corrected for the first time, boosting hopes for the development of new drugs which could one day slow or prevent the currently untreatable condition.

Results from the ground-breaking research, conducted by scientists from University College London, showed how an experimental drug was effective in lowering levels of toxins in the brain which cause Huntington's - one of the most devastating neurological disorders.

Huntington's is a hereditary condition and affects around 8,500 people in the UK. It causes damage to brain cells, eventually leaving patients in a vegetative state. Before this stage, patients' cognitive abilities and motor skills are severely affected. Most sufferers die ten to twenty years after the first symptoms appear – which commonly occurs in their 30s and 40s.

At present, there is no cure and current treatments are only able to manage the symptoms.

The disease is caused by a mutation in a gene that is responsible for producing a protein called huntingtin which is crucial for brain development. The genetic error changes the functioning of this protein, causing it to become toxic to brain cells.

The new treatment, which takes the form of a drug injected into the fluid around the spinal cord, suppresses the action of the troublesome gene. It was developed by drug company Ionis Pharmaceuticals who said that the treatment had "substantially exceeded" expectations.

The trial, which involved 46 patients, demonstrated that the drug safely and effectively reduced levels of the toxic huntingtin protein in the brain.

"The results of this trial are of ground-breaking importance for Huntington's disease patients and families," said Sarah Tabrizi, Director of UCL's Huntington's Disease Centre. "For the first time a drug has lowered the level of the toxic disease-causing protein in the nervous system, and the drug was safe and well-tolerated. The key now is to move quickly to a larger trial to test whether the drug slows disease progression."

The researchers note that the results of long-term studies, which are currently underway, are needed to determine whether reducing the levels of the toxic protein can slow or prevent the disease in the long run – something which animal experiments have suggested.

Full results from the latest trial will be published next year.

Philippa Brice, from health policy think-tank PHG Foundation, added: "This is a potential game-changer, not only for Huntington's disease patients but also for genomic medicine in general. Though more work needs to be done, if gene silencing lives up to this promise we could be on the brink of some of the personalised treatments that patients with severe genetic diseases need so badly. But this will also raise further questions for society and for policy-makers about how best to use such a powerful technique."