NEW YORK (Reuters Health) - Researchers have uncovered the function of a protein that plays an important role in Huntington's disease (HD), a finding that may provide new clues on how to treat the disorder.

Huntington's, an inherited disease of the central nervous system, usually surfaces between the ages 25 and 55. The brain gradually deteriorates, causing initial symptoms such as involuntary movements and balance problems. As the disease worsens, vital functions like speaking and walking may decline.

Huntington's disease is thought to involve a mutated version of a protein called huntingtin, which is responsible for destroying the brain tissue. Researchers have believed the mutation somehow caused the protein to be toxic. But until now, they have not been able to identify the function of the ''normal'' huntingtin protein present in people without the disease.

Dr. Elena Cattaneo, from the University of Milan, in Italy, and colleagues found that the huntingtin protein controls the production of another protein called brain-derived neurotrophic factor (BDNF), which is essential for maintaining the type of brain cells that die off in patients with Huntington's.

According to the researchers, patients' mutated huntingtin protein cannot produce proper amounts of BDNF, which leads to brain deterioration.

``We found that normal huntingtin activity is gone in the disease due to the mutation in the gene,'' Cattaneo told Reuters Health. ``Prior to this we thought that Huntington's was due to a toxic activity caused by the mutant protein. Here we show that there is a loss of normal function.''

Writing in the June 14th issue of Sciencexpress, the online edition of the journal Science, the researchers note that increasing BDNF levels may benefit Huntington's patients. Therapeutic drugs aimed at mimicking or increasing the normal activity of huntingtin protein may be effective in treating the disease, they conclude.

``We now need to look at drugs that mimic the action of normal huntingtin, increasing the production of BDNF,'' Cattaneo said. ``There must be a cure for this disease,'' she added, ``and there must be one very soon.''