7. Somewhere out in the future there's a final moment with our name on it: life's only certainty is death. It's coming, and the only mystery about mortality's last call is: when? But if your doctor could tell you, would you want to hear how long you are likely to live? American researchers now believe that they are able to determine a person's "natural" life span from a simple blood test. They have identified the ability of a common gene to influence the ageing process, and the form it takes in any given individual can they say, indicate medical vulnerability and predict when the person may die. The news has created much excitement but it also has raised concerns about the ethical dilemmas involved if science is able to read our lifelines and forecast our susceptibility to deadly diseases. It's a development that revives the eternal question: should a doctor tell?
Apo E, as it's known, is not a new discovery but, hitherto, scientists believed that its only function was to remove cholesterol from the bloodstream. Only lately as they have been able to study the ever increasing numbers of elderly, has the gene's relationship with longevity become apparent. It apparently operates as a kind of caretaker
gene, maintaining the system's cells and keeping them running smoothly, and its efficiency can determine the rate at which the body holds up or wears out. "Apo E is one of those genes that we suspect controls life span because it affects people’s susceptibility to diseases of ageing”, says Dr Jan Vigh; a molecular geneticist at Beth Israel Hospital, in Boston. The gene has three variants, known as E2, E3, E4, and we all inherit one of them from each of our parents. More than half of us are born with two E3s, but it is the distribution of the other two forms that has proved so compelling to scientists that they have been analyzing data on the elderly.
People with one or – more rarely – two E2s tend to survive the longest, while those with E4s die considerably earlier than the rest. Studies in Canada, France, Sweden and Finland found that E2 carriers were about four times more likely to reach their 100th birthday than those born with an E4. The E2 is, it seems, an excellent caretaker. By
comparison, E4 does sloppy work and its inadequacies at cell upkeep make those who have it vulnerable to illness and early death. Doctors now accept that the presence of the Apo E4 gene signals a risk of heart disease and Alzheimer's. American studies show that middle aged women with an E4 are twice as likely to develop coronary
heart disease as those who don't, while E4 men have a 50 per cent higher risk than other men. Among men under 40 who require surgery for clogged heart arteries, the incidence of two E4s is 16 times higher than among others in their age group And Dr Alan Roses, the Duke University neurologist who first made the link between Apo E and Alzheimer's, says those with two E4s have about six times the normal risk of developing the disease, while people born with two E2s may be protected from it.
More than 4 million Americans are afflicted by this devastating brain disorder and nearly two-thirds of them have at least one Apo E4 gene, compared with only 15 percent in the general population. So Apo E may be a critical marker for life span and vulnerability to grave diseases, and evidence of its presence is in the records of millions of blood tests conducted for other reasons. But is it ethical or wise for doctors to use that information to tell people something they may not want to know and which, in any case, alerts them to threats that may be unavoidable? “We consulted bioethicists and got a variety of opinions," says Dr Norman Relkin, the New York neurologist who gathered other concerned doctors to discuss the issue at a conference in Chicago. After two days, they called for more research to establish the nature and the risks of the Apo E family but many researchers seem opposed to confronting people with alarming news about conditions that cannot be fought, based on blood samples given for other purposes.
"Have you done them a service?" asks Dr Lindsay Farrer, an Alzheimer 's researcher at Boston University Medical Centre. "What good does it do to tell someone about being at risk from a dreaded disease that can neither be prevented nor effectively treated?" Dr Rudolph Tanzi, an Alzheimer's specialist at Massachusetts General Hospital,
agrees but, because his own family has a history of early heart problems, he was unable to resist having his own Apo E analyzed. He is an E3, in the same wide, neutral middle ground as most of humanity. The problems raised by Apo E are varied and complex. Some doctors worry about possible discrimination from employers and insurance companies if people are routinely told they may have a predisposition to serious illness and premature death. Because blows to the head seem to increase the risk of getting Alzheimer's among people with the E4 gene, should boxers and other athletes, and children wanting to play contact sports, be tested for their Apo classification? “Already!”, says Dr Relkin, pregnant women are asking for their fetuses to be screened so they can consider abortion if their babies show two E4s.
Duke University's Dr Roes is working with a major drug company to try to define what gives Apo E2 its ability to improve the body's defenses, so that its protection can be duplicated in the laboratory. "The hope is that we shall be able to make a drug that does what Apo E2 does," he says. Meanwhile, for millions of people around the world, their destiny -how they will live, when they will die is perhaps already foretold in a dusty medical file.
Researchers have identified ______