Researchers at the Garvan Institute of medical research in Sydney have collaborated with researchers from Australia, UK and Israel to develop a new DNA test that identifies a range of neurological and neuromuscular genetic diseases that are hard to diagnose, quickly and incredibly accurately.
From Huntington’s disease, fragile X syndrome, myotonic dystrophies, myoclonic epilepsy, hereditary cerebellar ataxias to motor neuron diseases and more, this test correctly diagnosed all patients in the study.
The test identifies diseases that are caused by unusually long repetitive DNA sequences in genes - therefore called as short tandem repeat (STR) expansion disorders.
John, A participant in the study whose symptoms caused him to go from an active skier to needing support to walk, finally managed to get a diagnosis. The test unlike all the previous ones he took, diagnosed him with a rare genetic disease called CANVAS which affected his brain. For patients like John, the test would be a game changer and an end to what can often be a very taxing diagnostic odyssey.
As repetitive expansion disorders are genetic, they are passed on through families and can be fatal and normally involve muscle and nerve damage and other complications. This quick and accurate diagnosis test avoids this diagnostic odyssey - the odyssey that makes it problematic for patients to be diagnosed with what they have.
The current testing module can be a Hit-and -miss as each genetic disorder has to be separately tested based on the symptoms and family history. With the new test, all diseases can be tested in a single DNA test and a clear diagnosis can be achieved avoiding years of unnecessary muscle or nerve biopsies or risky immune system suppressing treatments.
Using Nanopore sequencing technology the patient’s genome is scanned using a single DNA sample extracted from their blood. This technology is cheaper than the current standard tests and so the transition to commercial laboratories should be smooth.
"In the one test, we can search for every known disease-causing repeat expansion sequence, and potentially discover novel sequences likely to be involved in diseases that have not yet been described," says Dr. Deveson
DR IRA DEVESON OF THE GARVAN INSTITUTE OF MEDICAL RESEARCH.
CREDIT: GARVAN INSTITUTE OF MEDICAL RESEARCH
According to Dr Deveson with this technology, the gene sequencing device will be the size of a stapler instead of the size of a fridge, which is the standard and will cost around thousand dollars each compared to the usual hundreds of thousand dollars.
He and his team also believes this technology should be used in regular diagnostic practice within the next few years.
One of their main goals is gaining appropriate clinical accreditation for it. Once that has been achieved, the test will also become a medium for research into other genetic disorders, mainly adult- onset genetic disorders that haven’t received as much research attention as those that appear in the natal and early stages.
Reference:
Igor Stevanovski et al, Comprehensive genetic diagnosis of tandem repeat expansion disorders with programmable targeted nanopore sequencing, Science Advances (2022). DOI: 10.1126/sciadv.abm5386. www.science.org/doi/10.1126/sciadv.abm5386
Journal information: Science Advances
by Meher Biju
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