A year ago, I joined one of the most exclusive clubs in Britain. After wiping a swab around the inside of my cheek, and swiping my credit card to the tune of $985, I became one of the first people in the country to get a good look at the contents of my genetic code.

The companies that sell such DNA tests directly to consumers are coy about customer numbers, but at current prices it is a fair bet that no more than a few thousand have yet signed up. My membership of the genome club, however, is not going to remain exclusive for very long.

DNA profiles for all might sound like something from the science fiction world of Gattaca, but the plummeting cost of the necessary technology, and the increasing value of the medical insights they can provide, mean they are coming, and faster than you think.

In the year since I took my test, which examined a million DNA letters for variations with health implications, such services have more than halved in price. Most geneticists predict that, within a couple of years, it will be possible to sequence all six billion letters of an individual's genome for less than $1,000. Such profiles will soon be affordable for anyone who wants one - and many believe that the NHS will be paying for them within a decade.

As these genome scans become cheaper, they also reveal more and more meaningful information about health. More than 400 common genetic variations are now known to affect people's risk of serious conditions, including heart disease, diabetes and many cancers; new links between genes and disease emerge every week, along with new information about reactions to drugs.

These developments have brought us to the verge of a revolution in personalised medicine, by which treatment and prevention are tailored to an individual's genetic make-up. Its delivery, however, will depend on the ability of doctors, particularly GPs, to interpret their patients' DNA data and use it wisely in clinical practice. And there is little evidence that the medical profession is ready.

All doctors receive some training in the basic concepts of genetics and their implications for primary care. The existing syllabus, however, is founded on the way that genetics has affected medicine in the past and not on the challenges it will create in the future. The result is that doctors are not learning skills that would help them to practise effectively in the genomic age.

At present, genetic training focuses on Mendelian diseases - rare mutations in single genes, which usually have severe effects. People who inherit the Huntington's mutation, for example, will invariably develop the fatal brain disorder, while 80 per cent of women who have a mutated BRCA1 gene will contract breast cancer.

This focus is perfectly understandable. Doctors need to understand and recognise these disorders, even if they will see few cases. Until recently, too, Mendelian conditions were the only ones for which genetic roots had been properly established. A knowledge of these rare diseases, however, is not going to be much help when patients start to visit their GPs waving printouts from genome scans like the one I took.

These genetic scans look at hundreds of thousands of common genetic variations, most of which do not do much on their own. Some combinations, however, can appreciably raise or lower people's chances of developing diseases and traits, from Alzheimer's and bowel cancer to male-pattern baldness. This type of genetic testing produces results that are fuzzy and based on probability, rather than deterministic and diagnostic. That makes them devilishly difficult to interpret.

Sometimes, they may identify inherited predispositions that are useful in preventive medicine, leading to refined screening programmes and lifestyle interventions to promote health. They can also promote needless alarm or false confidence. Doctors will have to decide case by case whether a woman with an elevated genetic risk of breast cancer should be reassured, or advised to start taking mammograms earlier than usual. They will also need to manage the anxieties of patients who discover they have a high risk of Alzheimer's, and the overconfidence of smokers who think that their genes protect them against lung cancer.

These are going to be difficult issues for GPs to explore in ten-minute consultations. Yet they are currently offered no preparation for this in their training.

This is not the only way in which medical education fails to address gathering genetic challenges. Genetic variation affects the body's response to drugs as well as its risk of disease, and as doctors gain access to details of their patients' DNA, they will have to change the way they prescribe.

The DNA-based approach to treatment, known as pharmacogenomics, is already used in cancer, as drugs such as Herceptin work only against tumours that carry a particular mutation. In time, it should also prove useful in the management of conditions such as diabetes and heart disease: these have diverse genetic roots, which suggest that not all patients will benefit from the same therapeutic strategies. Individuals' genes also affect the way they metabolise drugs, such as statins, and can already be used to optimise doses and avoid dangerous side-effects. Such insights are going to make medicine safer and more effective. Doctors need to learn how to exploit them.

As Yogi Berra, the sage of baseball, said: “It's tough to make predictions, especially about the future.” Personal genomics is in its infancy, and with new discoveries emerging all the time, we cannot yet know the detail of what tomorrow's doctors will need to know. They do not need to learn about every variant that has been linked to a disease risk or drug response: that knowledge remains incomplete, and it can always be looked up.

What they do require, however, is an appreciation of how genetic discoveries are likely to become integrated into medical practice, and basic skills to make the most of them.

When doctors prescribe drugs, they already know to check what else patients are taking so they can avoid potentially harmful interactions. They need to learn that, before long, it will be just as important to check their genotypes. GPs are already proficient at explaining what raised cholesterol or blood pressure means for a patient's health. They will have to become as comfortable interpreting the more complex risks that are revealed by genome scans.

The opportunities that genetics offers for better medical care will be matched by fresh demands on medical practitioners. If genetics is to become embedded in clinical practice, it must also be embedded in clinical education.

Mark Henderson's 50 Genetics Ideas You Really Need to Know is published by Quercus at £9.99. To buy it for £9.49 inc p&p call 0845 2712134 or visit timesonline.co.uk/booksfirst

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