TRANSPLANTING brain cells into patients with Huntington’s disease produced long-term benefits, a French team reports today.

Huntington’s is a genetic disease that is caused by a defect in the gene that produces a protein. Its effects — gradual but inexorable damage to the brain that causes physical, mental and emotional changes — are not usually obvious before the age of 30 to 50, by which time many carriers of the gene may have had children and passed on the condition.

Anyone who carries the gene will eventually develop the disease, which has no cure. It follows a course over ten to twenty years of decline to helplessness. About 4,800 Britons have Huntington’s.

One possible treatment is to inject foetal cells into the brain to replace those damaged by the disease. Stem cells may one day take the place of the foetal cells and perform similarly.

Researchers at the Henri Mondor Hospital in Paris, whose findings are published in The Lancet Neurology, carried out foetal-cell transplants in five patients in 1998. They reviewed the patients’ progress after two years and found that movement and brain function had improved in three.

They now report further on these three and suggest that the transplants provided several years of improvement. But the treatments did not cure the disease. After plateauing for two years, symptoms began to worsen, although the rate of decline varied.