The Huntington's Disease Society for America describes the condition as "a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain". Usually starting in middle age, it can quickly see people lose control of their mental capacity and body movement.
Cath Stanley, chief executive of the Huntington's Disease Association, says in an emailed statement: "Today's announcement of the results of the trial are of ground-breaking importance to families affected by Huntington's disease".
Peter Allen, 51, is in the early stages of Huntington's and took part in the trial: "You end up in nearly a vegetative state, it's a disgusting end". The improvements increased with each larger dose, indicating its benefits in treating the disease.
Researchers at University College London have shown that an experimental drug successfully lowers the harmful huntingtin protein - which is vital for brain development - in spinal fluid. "This is presumably the most noteworthy crossroads in the historical backdrop of Huntington's since the quality [was isolated]".
The results caused ripples across the scientific world as the drug, which is a synthetic strand of DNA, could potentially be adapted to target the incurable brain disorders such as Alzheimer's and Parkinson's.
The next major step for Tabrizi and her research team is to conduct another trial, grander in scale and for a longer period of time, as the team was not able to determine whether the patients' clinical symptoms had improved.
But Prof Mallucci, who is the associate director of UK Dementia Research Institute at the University of Cambridge, cautioned it was still a big leap to expect gene-silencing to work in other neurodegenerative diseases. The patients were given four spinal infusions one month separated and the medication measurement was expanded at every session; around a fourth of members had a fake treatment infusion.
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Do you know anyone living with this disease?
The UCL trial is too small-scale to show whether the drop in toxic protein levels has alleviated the participants symptoms, but Swiss pharmaceuticals firm Roche has bought a licence to develop the drug further, The Guardian reports. The gene codes for a mutant protein known as huntingtin (mHTT) arelinked with the development of the disease.
"The case for these is not as clear-cut as for Huntington's disease, they are more complex and less well understood".
"But the principle that a gene, any gene affecting disease progression and susceptibility, can be safely modified in this way in humans is very exciting and builds momentum and confidence in pursuing these avenues for potential treatments".
The progressive neurological disorder, which now affects an estimated 10,000 people in the United Kingdom, is incurable - but an experimental drug, which has been shown to lower levels of the harmful protein responsible, could be a "game-changer". Most people with Huntington's inherited the gene from a parent, but about one in five patients have no family history of the disease.