Cause and Nature of the Disease.
The Huntingtin gene is on Chromosome 4.
Mutations in the gene produce variations in the number of CAG triplet repeats in one section of the gene. If there are more than 36 repeats then the person will develop the disease. It occurs in about 5 people per 100,000.
The disease become manifest in the fourth decade of life causing uncontrolled movements and dementia and death within twenty years.
The extra length in the gene results in the production of a defective protein that forms large clumps in the brain, and gradually kills off brain cells in parts of the brain.
Possible therapy routes are being developed.
Studies in mice have shown that reduction in the production of the defective protein can reduce the onset of the disease.
Prof. Beverley Davidson, working with her team in the University of Iowa, have made some outstanding discoveries in this area and produced some promising routes to therapies.
This possible route involves using a natural defence mechanism against viruses. "..short pieces of double stranded RNA (short interfering RNA's or siRNA) trigger the degradation of any other RNA in the cell with a matching sequence. If an siRNA is chosen to match the RNA copied from a particular gene, it will stop the production of the protein the gene codes for." (Bob Holmes, Gene Therapy conference, Banff, Canada, ca. 7th March 2003, New Scientist pg 20. 15th March 2003)
Beverley Davidson pointed out that you should not silence the gene completely. Brain cells may not survive without the protein, however we do normally have two copies of all genes, and if only on is defective then the normal gene will continue to produce the correct protein. The work they are doing at the moment is to find ways to silence only the defective versions of the gene.
Once fully developed this approach may be effective for other genetic disorders.
University of Iowa home page
Beverly Davidson page - overview of Prof. Davidson's research interests.
Beverly Davidson Lab - Team overview of the research areas covered
The Hereditary Disease
Foundation home page currently (24th Match 2003)
has links to extensive articles on the research into Huntington's Disease. for example;
Major Advances in Huntington's Disease Research Expected From Powerful Technology to Study Protein Structure;
Don't forget to also visit and search on the New Scientist web site.
This is a page from
www.genefaith.org created by A. J. Palmer.
This page was updated on 24th March 2003.