CHICAGO - A DRUG compound showed promise at reversing Huntington's disease in mice without the toxic effects seen in similar compounds, raising hope for a treatment for this fatal, hereditary brain disorder, US researchers said on Monday.

The team at The Scripps Research Institute in La Jolla, California, studied HDACi 4b, a modified form of a group of compounds known as histone deacetylase or HDAC inhibitors that have shown promise at treating the disease in animals.

Scripts scientists developed the compound, which is licensed to Repligen Corp of Waltham, Massachusetts.

'The agent proved to be therapeutically superior, as well as less toxic than other HDAC inhibitors that had been tested for Huntington's disease,' Dr Elizabeth Thomas, whose study appears in the Proceedings of the National Academy of Sciences, said in a statement.

Huntington's disease is caused by a mutated gene that makes an abnormal proteins that lead to widespread changes in the activity of genes throughout the brain. HDAC inhibitors prevent abnormal proteins from disrupting the activity of other genes.

The researchers studied the modified HDAC compound, HDACi 4b, in mice with the Huntington's disease gene. In these mice, symptoms typically appear at three months.

When the mice were four months old and their symptoms began to appear, the researchers added the compound to their drinking water. The drug dramatically improved the physical appearance and motor functioning of the mice, and it also kept them from losing body weight and brain volume.

When they looked for changes in the activity of genes in the brain, they found that many of the affected genes had become partially normalised and some were completely restored to normal status.

'This suggests that a treatment for Huntington's disease that targets a core pathogenic mechanism might be close at hand - closer than previously imagined,' Dr Thomas said.

Huntington's disease affects up to one person in every 10,000 in the Western world. It is a progressive, degenerative condition marked by uncontrolled movements, emotional disturbances and mental deterioration.

Drugs can help manage symptoms but do not stop the physical and mental decline. Patients typically die within 10 to 15 years after symptoms arise. -- REUTERS