Gene therapy for Huntington's disease?

A new study by US researchers suggests that gene therapy could be used to treat Huntington's disease (HD), a severe inherited brain disorder. Scientists at the University of Iowa have used a new technique to 'silence' the gene that makes the protein involved in HD in laboratory-grown human cells. 'When I first heard of this work, it just took my breath away' said Nancy Wexler, HD researcher and president of the Hereditary Disease Foundation in New York.

HD is caused by an alteration in a single gene, dubbed huntington, which makes a crucial brain protein. People who inherit a copy of the altered gene from an affected parent first develop symptoms of HD between the age of 30-50. The gene makes a defective protein that forms clumps in the brain, causing it to gradually waste away. Davidson and her colleague Henry Paulson used 'siRNA' (short interfering RNA) molecules to target and 'switch off' the huntington gene in human cells. Production of the defective protein fell by 80 per cent, whereas production of the normal protein was hardly affected. Previous studies have shown that reducing production of the defective protein in rodents can slow down the progress of the disease, and Davidson thinks the same could be true in people: 'If you reduce levels of the toxic protein even modestly, we believe you'll have a significant impact' she said.

The researchers, who presented their findings at a gene therapy conference held in Banff, Canada, believe their method could also be used to treat other inherited diseases. Even if both copies of a particular gene are faulty, they could be switched off and replaced with a working gene, reports New Scientist magazine.