New DNA test can detect 50 rare genetic disorders, researchers say

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Researchers in Australia say they have developed a new genetic test that can accurately diagnose 50 rare, life-threatening disorders. Photo by qimono/Pixabay

A new DNA test can accurately identify a range of hard-to-diagnose neurological and neuromuscular genetic diseases quicker and more accurately than currently available diagnostic tools, researchers at the Garvan Institute of Medical Research in Australia said Friday.

The diseases that can be spotted with the test belong to a class of more than 50 diseases caused by unusually long, repetitive DNA sequences in a person’s genes and are known as short-tandem repeat expansion disorders, the researchers said in article in the journal Science Advances.

Examples of the disorders include rare diseases such as Huntington’s disease, fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies and motor neuron diseases, including amyotrophic lateral sclerosis, or Lou Gehrig’s disease, they said.

The new test analyzes DNA in collected blood samples to spot disease-causing repeat expansion sequences, according to the researchers.

It works by scanning a patient’s genome using a technology called nanopore sequencing, the researchers said.

Although short-tandem repeat expansion disorders cannot be cured, earlier diagnosis can help doctors identify and treat disease complications sooner. These include heart issues associated with Friedreich’s ataxia, a disease that causes loss of sensation in the arms and legs, they said.

“In the one test, we can search for every known disease-causing repeat expansion sequence,” researcher Ira Deveson said in a press release.

These “are often difficult to diagnose due to the complex symptoms that patients present with … and limitations of existing genetic testing methods,” said Deveson, who is head of genomics technologies at the Garvan Institute for Medical Research in Sydney.

The test also can help “potentially discover novel sequences likely to be involved in diseases that have not yet been described,” he said.

Short-tandem repeat expansion disorders are passed on through families and can be life-threatening, according to the National Organization for Rare Disorders.

They generally involve muscle and nerve damage, as well as other complications throughout the body, and they can be challenging to diagnose, the organization says.

The nanopore-based test is programmed to analyze 37 genes known to be involved in short-tandem repeat expansion disorders and to read through the long, repeated DNA sequences that cause disease, according to Deveson and his colleagues.

The technology used in the test is smaller and cheaper than standard tests. It is about the size of a conventional stapler and costs less than $750, or a fraction of what other similar tests cost, the researchers said.

In this study, the device was used to evaluate DNA samples collected from 27 patients with known short-tandem repeat expansion disorders. In all patients, the test spotted the DNA sequences behind these disorders and correctly identified the specific diseases each patient had, the researchers said.

Assuming the findings can be reproduced in larger studies, they said they expect to see their new technology used in diagnostic practice within the next two to five years.

“For patients … the new test will be a game-changer, helping to end what can often be a taxing diagnostic odyssey,” study co-author Dr. Kishore Kumar said in a press release.

“Current genetic testing for expansion disorders can be ‘hit and miss,’ [and] can go on for years without finding the genes implicated in their disease,” said Kumar, a clinical neurologist at the Concord Hospital in Warrimoo, Australia.

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