Doctors are ill-prepared to deal with the advent of personal genome scans, which should give patients access to their complete genetic code within five years for only £1,000, leading ethicists and scientists said yesterday.

Although the ability to sequence individual patients’ genomes at affordable prices has the potential to transform healthcare, it poses clinical challenges that the medical profession has not yet thought through, according to an expert panel.

It took longer than a decade and more than £2 billion to sequence the human genetic code for the first time, but the cost has plummeted. The genome of James Watson, who with Francis Crick discovered the structure of DNA, was made public in May having been sequenced for less than £1 million.

Scientists now predict that the £1,000 genome should be a reality within five years, and would allow individuals to discover hundreds of inherited genetic variants, which might have implications for their health.

These personal genome records will indicate some variants that subtly affect people’s chances of developing a wide range of common illnesses, such as heart disease, diabetes and cancer. Often they will be able to lower their risk by changing their diet or lifestyle, or by taking preventive drugs.

Many of the health risks that genomic screening identifies, however, will be so slight as to have little clinical relevance. For example, a common variant that appears to raise the risk of heart disease by about 60 per cent was discovered this year. Although this increased relative risk sounds great, carriers’ absolute lifetime risk of heart disease was minimal, up only from 1 per cent to 1.6 per cent.

Writing in the journal Science, four leading scientists and ethicists, led by Dr Amy McGuire, of Baylor College of Medicine in Houston, have warned doctors that they need to consider how access to such information will affect how they treat patients.

The scientists are concerned that patients may expect to be given personalised health plans based on their “genetic MoTs”, yet the information that scans reveal will not always be up to this.

Knowledge that a particular genetic variant raises the risk of diabetes, on average, by 30 per cent is important to understanding the disease. But “just because an association between genetic variation and disease is statistically significant does not mean it is clinically meaningful”, the report says.

A main concern is that genomic scans will turn healthy people into the “worried well”, who want unnecessary treatments because they have misunderstood how genetics affects their risk of disease, and who could burden already-strained healthcare systems, the scientists say.

They add: “Guidelines should be developed, considering how best to use and present genomic information.”

Easily misunderstood

— Most people think of genetics as deterministic, that a mutation will invariably cause a disease

— But genome scans mainly reveal slightly raised average risks, for example that a person’s chances of developing heart disease may be 10 per cent higher than usual

— Such information is easily misunderstood: while the relative risk is raised, absolute risks may remain very low. This may make patients needlessly worried and unwilling to change lifestyle or diet

— There is a risk people will be misled into a buying expensive “genetic MoTs” that reveal little clinical importance

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