A single DNA test can now screen for more than 50 genetic diseases

When it comes to genetic neurological and neuromuscular diseases, screening early is key to getting the right treatment. 

A new DNA test developed by researchers at the Garvan Institute of Medical Research in Sydney may help in this process, as reported by the institution in a press release published on Saturday.

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The breakthrough could forever revolutionize how we diagnose genetic diseases, making the lives of patients easier and providing better treatment options.

A single DNA test

"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," Dr. Ira Deveson, Head of Genomics Technologies at the Garvan Institute and senior author of the study, said in the statement. 

Further research shows that the test is accurate and covers over 50 diseases caused by unusually-long repetitive DNA sequences in a person’s genes. 

Avoiding that diagnosis odyssey

Dr. Kishore Kumar, a co-author of the study and neurologist at Concord Hospital says the new test will allow patients to avoid what he calls the diagnosis odyssey.

"When patients present with symptoms, it can be difficult to tell which of these 50-plus genetic expansions they might have, so their doctor must decide which genes to test for based on the person’s symptoms and family history. If that test comes back negative, the patient is left without answers. This testing can go on for years without finding the genes implicated in their disease. We call this the ‘diagnostic odyssey’, and it can be quite stressful for patients and their families," he explained.

The new technology will bypass this entire process by giving immediate results through one single test. "This new test will completely revolutionize 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," Kumar added.

The team now hopes to see their new test used in diagnostic practice within the next two to five years by acquiring the appropriate clinical accreditation. Once accredited, the test will revolutionize how we diagnose and even treat genetic diseases.

The study was published in the journal Science Advances.

Study abstract:

More than 50 neurological and neuromuscular diseases are caused by short tandem repeat (STR) expansions, with 37 different genes implicated to date. We describe the use of programmable targeted long-read sequencing with Oxford Nanopore’s ReadUntil function for parallel genotyping of all known neuropathogenic STRs in a single assay. Our approach enables accurate, haplotype-resolved assembly and DNA methylation profiling of STR sites, from a list of predetermined candidates. This correctly diagnoses all individuals in a small cohort (n = 37) including patients with various neurogenetic diseases (n = 25). Targeted long-read sequencing solves large and complex STR expansions that confound established molecular tests and short-read sequencing and identifies noncanonical STR motif conformations and internal sequence interruptions. We observe a diversity of STR alleles of known and unknown pathogenicity, suggesting that long-read sequencing will redefine the genetic landscape of repeat disorders. Last, we show how the inclusion of pharmacogenomic genes as secondary ReadUntil targets can further inform patient care.