Searching for the Methusaleh gene

Man has reached an ever longer lifespan during the last 150 years. Life expectancy is still increasing by roughly 3 months for each birth cohort. This strictly linear trend has been documented since 1840. Thus, man has gained 40 more years of life expectancy since then and is continually gaining more. For 2060, an average life expectancy of one hundred years is assumed.
The ageing society is turning into a major challenge since age-related diseases and disabilities could well accompany the increase in life expectancy. "If it were possible to delay age-related disease symptoms for just one to three years per decade, a further increase in cases of illness could be prevented", Almut Nebel explains. To put this goal into reach, apart from environmental factors the genetic causes for ageing have to be explored first and foremost. Together with our individual living conditions, these parameters seem to influence life expectancy above all else, according to current knowledge.

It has already been proved that some genetic dispositions lead to a decreased or an increased life span. It could be shown that the nematode Caenorhabditis elegans carries a gene identified as "daf-2" which regulates the worm’s ageing. It seems to trigger a chain of events by sending out an initial message to receptors that pass it on until finally hundreds of genes are involved. Switching off "daf-2" results in the worm living twice as long. Similar manipulations of genes, for example in mice, flies or yeast, confirm the life-prolonging influence of individual variants.

Even if it does not look like it at first glance: genetically, man and worm are very much alike. Homo sapiens also carries "daf-2". In humans, this led to two genes developing over millions of years of evolution in contrast to invertebrates. Thus, results from animal experiments cannot simply be transferred to humans. They rather yield clues where in the genetic labyrinth the scientists should continue their search. Up to now, only one gene has been discovered that has an influence on ageing. For example, the epsilon-4 variant of the apolipoprotein E gene (APOE) raises the risk of Alzheimer's or coronary heart disease by a factor of four to five. The epsilon-2 variant on the other hand lowers that specific disease risk. It is this variant that can be found more often in people approaching their 100th birthday than in the general population.

Meanwhile, scientists are competing internationally to identify the next gene with an impact on ageing in humans. Scientific ambition is not an end in itself for the Research Group for Healthy Ageing, though: With a comprehensive understanding of ageing processes, the scientists in Kiel want to develop a new approach for the treatment of diseases which usually appear in older patients. Knowledge on genetic causes of serious diseases could be used to activate the body’s own repair programmes. Risk genes for specific disease patterns could be switched off. "Research on ageing", says Stefan Schreiber, director of the Institute for Clinical Molecular Biology, "can help develop a new perspective for growing old in good health and with a high quality of life. Ageing research provides an important contribution to sociopolitics so that we will be well equipped for the challenges of an ageing society."