THE researchers have pinpointed eight genetic variations that control the production of a crucial hormone, which is linked to old age as well as diseases of the elderly.They believe that by manipulating the Deoxy riboNucleic Acid (DNA), the genetic material, strands they could slow down the ageing process and ward off age related conditions.The genes control levels of the steroid dehydroepiandrosterone sulphate (DHEAS), one of the most abundant in the body and vital to many key functions.Levels of dehydroepiandrosterone sulphate (DHEAS) are known to peak in our mid to late 20s and then decline as we get older. By the time we reach 85, the body contains about five per cent of its peak amount.Researchers have established links between declining DHEAS levels and diseases such as type 2 diabetes and lymphoma, as well as, a decreased lifespan.A group scientists from across the globe analysed the DHEAS levels and 2.5 million genetic variants in 14,846 people from Europe and the United States of America (U.S.A).Results, published in PLoS Genetics journal, identified eight common genes that controlled the concentration of DHEAS, with some of those genes associated with ageing and age-related diseases such as type 2 diabetes and lymphoma.Researchers say their findings provide the first genetic evidence that DHEAS can cause common age-related diseases or a decreased lifespan. Supplements of the steroid have already been commercially available for the past few years.Dr. Guangju Zhai, the study author from Kings College, London, said that while taking it could theoretically slow down the ageing process, it was too early to say for sure how effective it could be.It is hoped that through manipulation or gene therapy we could slow down the ageing process or the affect of age related diseases, he said.Zhai and his team now plan to spend the rest of the year looking closely at each gene in the hope of discovering more. The next stage will be to identify which genes have which function, and which have a particular effect on DHEAS levels.Once this is identified that could be the next stage in coming up with technology to manipulate the genes and maybe even get the body to increase DHEAS levels itself.Prof. Tim Spector, senior co-author from Kings said, for 50 years we have observed the most abundant circulating steroid in the body, DHEAS, with no clue as to its role. Now its genes have shown us its importance in many parts of the ageing process.DHEAS, mainly secreted by the adrenal gland, is the most abundant circulating steroid in humans. It acts as an inactive precursor, which is converted initially into DHEA and thereafter into active androgens and estrogens in peripheral target tissues. In humans the serum concentration of circulating DHEAS is 100- to 500-fold or 1000 to 10,000 higher than that of testosterone and estradiol respectively.Unlike DHEA, which is swiftly cleared from the circulation and shows diurnal variation, serum DHEAS concentrations are stable and facilitate accurate measurement and diagnosis of pathology.DHEAS is distinct from the other major adrenal steroids (cortisol and aldosterone) in showing a significant physiological decline after the age of 25 and diminishes about 95 per cent by the age of 85 years.This age-related decline has led to speculation that a relative DHEAS deficiency may contribute to the development of common age-related diseases or diminished longevity.Low DHEAS concentrations are possibly associated with increased insulin resistance and hypertension, but not with incident metabolic syndrome. It is strongly associated with osteoporosis in women but not in men.Concurrent change in DHEAS tracks with declines in gait speed, modified mini-mental state examination score (3MSE), and digit symbol substitution test (DSST) in very old women but not in men. Low circulating DHEAS is also strongly associated with cardiovascular disease and mortality in men but not in women.A recent 15-year follow-up study showed that DHEAS was negatively related to all-cause, all cancers, and other medical mortality, whereas high DHEAS concentrations were protective. This has led to its widespread and uncontrolled use as a controversial anti-ageing and sexual performance supplement in the U.S.A and other western countries without any clear data about efficacy, potential risks or benefits.
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