Even after she passed the age of 100, Hendrikje van Andel-Schipper remained in remarkably good health. She had perfect eyesight until the age of 105. She remained mobile and alert with a good memory until just before her death at 115 in 2005.

A Dutch woman, she had attributed her good health and long life to clean living and a daily portion of herring. Since then, scientists who have examined her body have found something far more remarkable.

Andel-Schipper had the brain of someone 50 years younger. Many of the telltale signs of ageing, which in most people can already be seen in their thirties, were absent from her body. It was, the academics said, as though she was immune to damaging aspects of the ageing process.

Something more than herring had protected her — and scientists in America now think they are beginning to understand what it was. Researchers at Boston University believe they have identified groups of genes that determine longevity. With this information, they think they can predict, with up to 85 per cent accuracy, whether someone will live to 100 simply from looking at their DNA.

The breakthrough opens the door to the possibility of a blood test that could predict how long you will live. The implications are complex. Would you want to know how long your genes say you will last? What if the prediction proved wrong?

Like many other centenarians, long life seemed to run in Andel-Schipper’s blood. Her mother had been healthy right up until her death at 100 and her great-grandparents had far out-lived most of their peers.

Scientists had also noted that many of those who live past 100 do not lead particularly healthy lives; they have included smokers and those who did less exercise than people who died much younger. True, there are also people such as Fauja Singh, who last year ran a marathon aged 100. However, genes, not lifestyle or exercise, seem to be the key to longevity.

Thomas Perls, associate professor of medicine and geriatrics at Boston University and a lead author of the new studies, said: “For some time we have built up a body of evidence to indicate that exceptional longevity was a highly genetic trait.” But which genes? Perls and his team gathered data on more than 800 centenarians and analysed their medical histories. They established three distinct patterns of ageing.

Most people are susceptible to age-related illnesses such as Alzheimer’s or heart disease, which they contract as they get older and which often lead to death in the seventies or eighties.

In centenarians, the scientists identified one group that had developed some kind of serious disease before the age of 85 — but it did not kill them.“They delayed their disability well into their mid-nineties,” said Perls. “They just handle and deal with the same diseases much better than others do.”

Another group, the super-centenarians, were even more surprising. The average age at which they developed any kind of age-related disease or disability was 107. In other words, they escaped age related diseases and disability until the last tiny fraction of their extremely long lives.

To find out what made these supercentenarians different, the team mapped 250,000 markers in their DNA. They compared it with the DNA of 914 younger, healthy people and identified 281 markers that appeared to make individuals able to withstand the ravages of time better than others.

Many of the supercentenarians had just as many genes associated with old-age diseases as the rest of the population. However, they also had genes and genetic variants associated with longevity — which Perls believes may trump the effects of the other genes.

The team are now trying to understand what these “longevity genes” are doing in the hope that they might one day be able to create drugs that could mimic their effects.

Perls said: “My fervent hope is that if we can use this information to find out why these people are so incredibly different in terms of delaying or escaping age-related diseases, we may develop some pathways that will allow others to escape them too.

When King George V sent out the first telegrams to congratulate Britain’s centenarians in 1917 there were only 24 recipients. Now there are 12,640 people over the age of 100 in the UK and that figure is forecast to rise to half a million by 2066.

But for many, a longer life expectancy is not matched by good quality of life, and society is struggling to cope with the demands that imposes. If genetic analysis could forewarn us of our likelihood of resisting or succumbing to age-related diseases, it could prove useful to both individuals and the wider community.

Genetic profiling is already being used in the treatment of certain cancers. An individual's genetic code may be examined to determine whether or not a particular drug will be effective for them.

There are also firms that will take a sample of your DNA and, for a fee, offer to identify certain genes related to your chances of developing conditions such as Parkinson's disease or diabetes. Experts regard them as of limited value; Perls describes them as “quite frankly a scam”.Instead, for such predictive medicine to be effective it is essential, he says, to see the whole picture. The entire genome needs to be sequenced and there needs to be a database of controls to enable the results to be fully understood.

So far such whole genome mapping has been expensive and time-consuming. However, earlier this month a Californian company called Life Technologies announced it was developing a machine that could sequence a whole human genome in one day at a cost of $1,000 (about Rs 48,700). It aims to have a model in production by the end of the year.

When the right technology is developed, it will allow pharmaceutical companies to start collecting genetic data on a far wider scale, thus enabling more detailed analysis of the effects of different genes.

Perls said: “The hope is that down the road you could have this information on a credit card; the pharmacist or doctor would swipe that information and the computer would say, a person with this genetic signature, you should be on x, y and z [medication]”.

Could such information pose as many dilemmas as answers? In 2010 the Nuffield Council on Bioethics conducted research on the field of personalised medicine. It highlighted the dangers of mistakes being made and of diagnoses leading some people to adopt unhealthy lifestyles in the complacent belief that their genes would protect them.

Nikolas Rose, one of the authors of the report, said: “Genetic profiling services come with the promise that people will be able to take more responsibility for their health — but it is not clear what that responsibility would imply.

Elsbeth Juda, who is 100, lives in London and still takes pilates classes twice a week, has a clear view on the prospects for predictive medicine.

“I always assumed I would die young. If there had been a test to tell me I would live this long, I would never have wanted to know.”

It is life’s surprises, some say, that keep them going.