A new DNA test, developed by researchers at the Garvan Institute of Medical Research in Sydney and collaborators from Australia, UK and Israel, has been shown to identify a range of hard-to-diagnose neurological and neuromuscular genetic diseases quicker and more-accurately than existing tests.
Dr. Ira Deveson, Head of Genomics Technologies at the Garvan Institute and senior author of the study said:
We correctly diagnosed all patients with conditions that were already known, including Huntington’s disease, fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies, motor neuron disease, and more.
The diseases covered by the test belong to a class of over 50 diseases caused by unusually-long repetitive DNA sequences in a person’s genes – known as ‘Short Tandem Repeat (STR) expansion disorders’.
Dr. Deveson added:
They are often difficult to diagnose due to the complex symptoms that patients present with, the challenging nature of these repetitive sequences, and THE limitations of existing genetic testing methods.
The study, published today in Science Advances, shows that the test is accurate, and allows the team to begin validations to make the test available in pathology services around the world. Quicker, more-accurate diagnosis for patients avoids ‘diagnostic odyssey’.
Dr. Kishore Kumar, a visiting scientist said:
This new test will completely revolutionise how we diagnose these diseases, since we can now test for all the disorders at once with a single DNA test and give a clear genetic diagnosis, helping patients avoid years of unnecessary muscle or nerve biopsies for diseases they don’t have or risky treatments that suppress their immune system.
Although repeat expansion disorders cannot be cured, a quicker diagnosis can help doctors identify and treat disease complications earlier, such as heart issues associated with Friedreich’s ataxia.
Dr. Ira Deveson commented:
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. Using a single DNA sample, usually extracted from blood, the test works by scanning a patient’s genome using a technology called Nanopore sequencing.
The Nanopore technology used in the test is smaller and cheaper than standard tests, which the team hopes will smooth its uptake into pathology labs. The team expects to see their new technology used in diagnostic practice within the next two to five years. One of the key steps towards that goal is to gain appropriate clinical accreditation for the method.