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Genetic technology breakthrough gives hope to patients

People at risk of genetic diseases could have a better chance of diagnosis in the future after scientists successfully trialled new gene testing technology in Australian and New Zealand patients.

The groundbreaking study by the Murdoch Childrens Research Institute, Melbourne, and Broad Institute of Harvard and MIT, USA, used "next-generation" DNA sequencing to test more than 100 genes simultaneously to identify mutations that cause a group of rare genetic diseases.

Unlike current tests, which test one gene at a time, this technology allows scientists to screen many genes at the same time to establish a diagnosis more quickly and cost-effectively.

It is the first time scientists using the technology, which has been developed following completion of the human genome project, have published data from a large group of patient samples. The study was published online by Nature Genetics.

"Some conditions can be caused by mutations in a wide range of different genes, so testing one gene at a time can be a slow and expensive process and it is often not possible to sequence all relevant genes due to cost," co-author A/Professor David Thorburn said.

"Next-generation DNA sequencing methods could transform the diagnosis of genetic diseases by allowing us to test many genes at once, and this study shows that it can work effectively."

The study screened DNA samples from 103 patients, including some posthumously, for the most common form of mitochondrial disease, a genetic condition which causes death in up to 70 per cent of affected children and is linked to conditions including Parkinson disease and diabetes.

Using existing technology, a genetic mutation was identified in 43 patients, but the remaining cases were undiagnosed.

Scientists used next-generation sequencing to simultaneously screen 103 genes known or suspected to cause the disease from each patient sample. As well as re-confirming genetic diagnosis in the vast majority of existing cases, the testing identified diagnoses in 13 of 60 previously undiagnosed cases and also found two new disease genes not previously linked to mitochondrial diseases.

Professor Thorburn said the rate of diagnoses was likely to significantly increase in the future, with the technology expected to enable scientists to screen hundreds or even thousands of genes at once during routine medical testing.

He said the technology was also less invasive than existing testing methods.

"Because current testing can only screen one gene at a time, many children need to undergo painful muscle and liver biopsies to identify which genes should be tested, a process that can then take anywhere from a few months to several years.

"Next-generation sequencing can test many genes at the same time through a simple blood test. This will eliminate the need for biopsies in most patients and could give results in a matter of weeks."

Scientists estimate the cost of next-generation sequencing could be as little as $1000 per patient, the equivalent of the typical cost now for sequencing one gene in one patient.

The technology is expected to start being used in genetic diagnosis within the next two years.

However, further research is needed to improve the ability of scientists to interpret the genetic information quickly and more accurately.

(Source: Murdoch Childrens Research Institute: Nature Genetics)

Dates

Posted On: 16 September, 2010
Modified On: 28 August, 2014


Created by: myVMC
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