Monday, 17 October 2011 00:47
Dutch researchers have sequenced the genome of a woman who lived 115 years. Presenting their findings at a conference in Canada last week, they said they hope the information will provide a useful reference point for studies of longevity and health in old age.
Dr Henne Holstege of the Department of Clinical Genetics at the VU University Medical Center in Amsterdam, and colleagues, did not reveal the woman's name, they refer to her as W115. At the time of her death she was the oldest known person in the world, and throughout her life showed no signs of vascular disease or dementia.
W115 came into the world as a premature baby, and was not expected to survive. But she lived a long and healthy life.
She donated her body to science, allowing scientists to study her organs and brain, and also map her DNA.
She was treated for breast cancer at the age of 100, and at age 112-113, she underwent "neuropsychological examinations" that showed her mental capacity was better than the average of people aged 60-75 years.
A post-mortem examination revealed that she had died of a stomach tumor.
The researchers were amazed to discover that her arteries showed almost no signs of plaque or atherosclerosis, which is one of the leading causes of death in older people (the vascular dementia that is linked to it is a leading cause of dementia).
The researchers used the opportunity of W115's generous donation to assemble "a unique genome specific for the coding of a long, healthy life", and create an "accurate biological reference genome for longevity projects".
Using DNA sequencing methods such as "paired end and long mate pair reads", adding up to more than "120x genomic coverage", they compiled an extensive catalogue of all W115's variants, including "SNVs, CNVs, and large and small structural variations".
Thus they have produced a map that could potentially show which of W115's unique genes or variants may have contributed to her longevity and apparent good health and mental function in old age.
The research is still in its early days, and Holstege and colleagues intend to publish what they find to make the genome sequence available for scientific research.
An initial analysis, however, has already established that W115 had some rare gene variants that are known to be linked to atherosclerosis, heart disease, Parkinson's Disease and Alzheimer's Disease.
It is not clear yet what role these genes played in W115's genome, but Holstege suggested, in an interview with the BBC, that she may have had something in her body that protected her against dementia.
"We think that there are genes that may ensure a long life and be protective against Alzheimer's," she added.
Written by Catharine Paddock PhD