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Geneticists predict that complete DNA sequencing will become part of mainstream medicine

Geneticists are predicting that within five years, a single genetics test will show what diseases might await us as we get older.

Hans Brunner, professor of medical genetics at Radboud University Nijmegen Medical Centre in the Netherlands, has said that the availability of comprehensive genetic testing is close.

“The technology is now available to test for all genes in one go and it is becoming more affordable,” said Brunner. For instance, while now it costs about €1,500 for individuals to have a complete sequencing of their DNA (all the genetic information in our cells) to predict what diseases they might be at risk of getting as they age, Brunner predicts such tests will become available in GP surgeries at a cost of €50.

“Genetics will come at the beginning of the diagnostic odyssey so you might find out your risk for something you’re not even looking for,” Brumer told a talk in Dublin last year. “Instead of having specialist clinics like we do now, genetics will become part of normal medicine and you will only be referred to a specialist clinic when your disease is identified. Rare disease centres will become crucial.”

Complete sequencing

Prof Andrew Green, director of the National Centre for Medical Genetics and consultant clinical geneticist at Our Lady’s Children’s Hospital, Crumlin, agrees the technology is now available for such complete sequencing of an individual’s DNA.

“I’m not sure it will be quite as cheap as Prof Brunner suggests – maybe €100-€300 – and while the test can be done by any physician, doctors are currently not trained to deal with the information the test results will bring,” says Green.

He says there are no plans to introduce total DNA sequencing tests directly into the healthcare systems. However, individuals can have their DNA sequenced privately for the sum mentioned above. But even if the technology is already available, this doesn’t mean the results from DNA sequencing will be easy to interpret or act on, according to Green.

Genetic testing is only carried out once a disease or inherited disability has been found in an individual. So, for example, when breast cancer is found in members of one family, their siblings, children and cousins can avail of genetic testing to see if they have the gene mutation that carries the risk of breast cancer.

“In the future, we will look at all the genes linked to inherited diseases. So, for instance, at the moment, we focus on one or two genes for inherited heart disease and there are 50-100 known genes for inherited heart conditions. Similarly, there are several hundred genes for inherited eye diseases and about 80 genes for inherited deafness and hundreds of genes for neurological diseases and we only look at a couple of genes once we see the problem clinically,” explains Green.

Brunner also points out the huge educational journey needed before DNA sequencing is made generally available. “All medical doctors will have to learn to work with the knowledge of genetics and the emphasis will shift to educating doctors about genetics. We will all have to learn how to manage the information that genetics tests bring,” he says.


So, how will people manage this new level of information about their genetic susceptibility to certain conditions? Some people opt out of genetic testing for conditions they may be at risk of. But, if other family members opt in, this can cause stress and uncertainty to everyone involved. Also, the ethics of who has a right to know what diseases they are at risk of getting is a further concern for people.

The inherent problem in all of this is that it puts the onus on the individual to choose whether to act on their risk profile. For example, some women choose to reduce their risk of getting inherited forms of breast cancer by having a double mastectomy. Others not. “The biggest issue will be that although we will be able to sequence larger numbers of genes, making that information clinically useful will be the challenge,” says Green.

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