THE first human gene known to affect the ageing process has been identified, unlocking a range of opportunities - and ethical dilemmas - for medical science.
The research provides the first glimpse of the genetics of why we age . Some scientists believe it may help to curb the cost of caring for the elderly by making them healthier, or point the way towards treatments for grey hair, wrinkles, deafness and fragile bones.
But others fear a nightmare future in which lifespan is extended without maintaining quality of life, when genetic tests can detect maximum life expectancy, putting those with a poor outlook at a disadvantage when seeking insurance or a mortgage, or a foetus with a short expectancy to be aborted.
A team from Darwin Molecular Corporation, a Seattle biotechnology company, and Dr Gerard Schellenberg's team at the Seattle Veterans Administration Medical Research Centre, announce today in the journal Science that they have found the gene for a rare hereditary disease, called Werner's Syndrome, that causes premature ageing.
Those born with the syndrome begin to age in adolescence. They become grey, develop wrinkled skin, then lose their hair and become susceptible to diseases associated with the elderly, such as cataracts, heart disease, diabetes and cancer, usually dying before the age of 50.
"This is the first time that any gene that has been associated with ageing has been identified," said Dr David Finkelstein of the US National Institute on Ageing .
The discovery of the defective gene responsible for the syndrome offers an insight into ageing and may explain why some people age faster than others. An individual must inherit a copy of a particular gene defect from both parents to develop Werner's. But Dr Schellenberg is now seeking carriers of that mutation, thought to be around one in 200 people, and other mutations in the gene that may have a more subtle effect on ageing.
Importantly, variants in the gene could affect an individual's risk of major age-related diseases, such as heart disease, cancers, the osteoporosis that causes brittle bones, adult diabetes and cataracts. "It's not only an ageing gene: it's a cancer gene," commented Prof Robert Miller of the US National Cancer Institute.
The Werner's Syndrome gene has been found to be the code for a helicase, one of a family of enzymes that play a crucial role in manipulating genetic material - the molecule DNA - during the process of cell division.
The helicase unwinds the two strands of the DNA double helix. This enzyme is defective in Werner's patients, which suggests that the processing and handling of DNA information in the cell plays a central role in the complex ageing process.
The defect in DNA metabolism could be linked to abnormally fast cell division, or boost the decay of telomeres, structures at the end of chromosomes linked to ageing. Whatever, ageing is a process that depends upon a huge range of genes.
"While the full significance of this gene discovery is not yet clear, it is expected to lead to a fundamental understanding of the molecular and cellular basis of the ageing process and to the identification of novel components of the pathways that lead to major age-related diseases," said Dr David Galas, Darwin's Chief Scientific Officer.
