Taking a Family History
Taking a family history….
Jane Feinmann wonders whether its
healthy to investigate the state of ancestral arteries.
That’s certainly the advice of American doctors. The US Surgeon General, Dr Richard Carmona recently urged his fellow Americans to use family reunions such as Thanksgiving dinners as an opportunity "to trace illnesses suffered by parents and other blood relatives". The more information each person is able to collect, the more useful it will be, he explained. Already, nearly a million people have complied, entering the information they gather into an interactive website (http://www.hhs.gov/familyhistory), to draw up a "health graph" that they can show to their doctor.
On the face of it, Americans’ desire to get their genes out in the open seems sensible. A study has shown, for instance, that one in eight American families account for half the number of heart attacks. Whether such families inherit a tendency to high blood pressure or share a preference for junk food is beside the point: knowing you belong to such a family is the start of making the right changes. "Getting advice from your doctor on preventing premature death from heart disease has more of an impact when you can see your risk of developing the disease in a graph in front of you," says Dr Mike Murray, clinical chief of medical genetics at Boston's Brigham and Women's Hospital.
British doctors are more sceptical of the benefits of making us overly conscious of our susceptibility to disease. Health psychologists say that there is not enough evidence yet to know how people will react to more knowledge about their genes. "Learning more about your genetic risk, whether it's through a DNA test or getting to know more about your family history, could be motivating, or it may make you fatalistic," says Professor Theresa Marteau, director of the Psychology and Genetics Research Group at King's College, London.
A recent British Medical Journal cartoon summed up concerns about how we respond, with a picture of two ageing ladies smoking and boozing, one saying to the other: "Cancer? Frankly darling, I just don't have the gene for it" - to which the other replies: "Well actually, darling, I do, but I simply don't care."
Professor Marteau is currently investigating the impact of genetic information on behaviour in two large trials, and until they are completed, she says, there is not enough evidence to suggest which people will benefit from getting different kinds of information and advice. What's more, even the Wisconsin geneticists acknowledge that a full knowledge of one's own genome will not bring cures or effective prevention of these distant threats, but merely "allow doctors to give personalised advice on their diets, lifestyles and medical check-ups". The concern in the UK is that this development will lead to an increase in the growing number of worried well with a ratcheting up of anxiety levels for precious little gain.
Take my own family. Reasonably close relatives have had breast cancer and I’m aware that this increases my risk of the disease: having one close relative develop cancer at any age increases an individual's risk of developing cancer by around 14 per cent, in someone with two close relatives with cancer, the extra risk is just over 20 per cent.
It’s also possible that I might carry one of the two breast cancer gene mutation that have so far been identified (BRCA1 or BRCA2). If so, that would push up my lifetime risk of developing breast cancer from about one in 12 (the average lifetime risk for a woman in the West) to a much scarier four in five.
From my point of view, such
knowledge is useful as long as I keep it in proportion. It’s a
useful reminder to have a mammogram in order to pick up the
disease as early as possible – something that’s free and yet
thousands of women fail to turn up at a mammogram appointment
every week. On the other hand, I am not going to worry about
having breast cancer – what’s the point? Nor would I consider
drastic action: a double mastectomy for instance that might
reduce my risk slightly or IVF for the next generation to screen
away a foetus carrying the gene.
Behind my own scepticism about being overly gene-conscious, is the awareness that there is a developing industry with a vested interest. Genetically tailored smoking-cessation and weight-loss products are already in the pipeline. And the new science of "nutrigenomics", with a range of food products tailored to people's genetic profile, is already causing waves of excitement at scientific conferences around the world.
Alongside the buzz, however, is concern about how expensive such
products are compared to more mundane but potentially more
effective strategies. "The idea of investing public funding in
individualised nutritional products that tweak beneficial or
undesirable aspects of our genetic predisposition is absurd in a
country with a high incidence of saturated fat-related disease -
especially in a country that is failing to take action to reduce
the production of fatty foods," says Tim Lang, professor of food
policy at City University.