Personalised care one step closer as Mayo Clinic sequences patients' genomes

Personalised healthcare could be one step closer this year, as doctors from the prestigious US Mayo Clinic embark on a project to sequence the full genetic code of thousands of people.

In an ambitious move towards an era of 'proactive genomics', volunteers will have all six billion letters of their genome (or a subset of genes that are linked to diseases) read, stored and linked to their medical records. Another group of patients will be tested for 83 genes that govern how the body metabolises drugs.

'We are convinced that whole genome sequencing is going to radically change the way we practice medicine', Dr Gianrico Farrugia, director of the Centre for Individualised Medicine at Mayo Clinic, explained to the Guardian.

By using the information contained within a patient's whole genome, it is hoped doctors will be able to take a more proactive step towards prescribing specific drugs and therapies. The intention is to allow more targeted, effective and beneficial treatments to be used.

Throughout the trial doctors will keep track of the patients and their prescriptions to see whether whole genome sequencing, or more limited genetic testing, benefits them or reduces the costs of their treatment.

Using genetic information to steer patient treatments is not a new concept, specific genetic tests are already used in many clinics. However, such tests are reactive — for example when a patient fails to respond to a drug or experiences an adverse reaction — and only test for what is known.

Dr Farrugia explained: 'The advantage of whole genome sequencing is that you go after everything. Not only does that give you a fuller picture, but it allows you to draw complex interaction pathways that you cannot draw by going after select genes'.

The study will help managers at the clinic decide whether it is better to read and store a patient's whole genome early on, instead of ordering single genetic tests as and when the need arises. Dr Farrugia gives the example of a heart medication where the presence of a single gene that prevents them from processing it properly. By using whole genome sequencing, doctors would be able to check for the gene before choosing which drug to prescribe.

Furthermore, with the cost of full genetic sequencing having fallen so rapidly in recent years, it is now comparable to the price of a test on a single gene.

However, Professor Anneke Lucassen of Southampton University cautioned that 'although the cost of a full genome sequence is getting to be very affordable, robust interpretation of what it means for an individual lags behind. There's a lot of promise about tailoring treatments, or modifying lifestyles, depending on particular genetic variation, but to date, with a few exceptions, the clinical utility of genome sequencing is limited'.

The trial also aims to assess how best to store and explain the information to patients, but, with such a ground-breaking study, the ethical implications cannot be overlooked.

'There are some significant ethical and privacy issues and they are probably more difficult to solve than storing the information', commented Professor Tim Aitman, of Imperial College London.