Single test for over 50 genetic diseases to cut diagnosis from decades to days

A single DNA test has been developed that can screen a patient’s genome for over 50 genetic neurological and neuromuscular diseases such as Huntington’s disease, muscular dystrophies and fragile X syndrome.

The test, developed by a team including Dr Andrea Cortese and Dr Henry Houlden, both of UCL Queen Square Institute of Neurology, and led by the Garvan Institute of Medical Research in Sydney, has been shown to identify a range of hard-to-diagnose neurological and neuromuscular genetic diseases more quickly and accurately than existing tests.

In a study, published in Science Advances, the test correctly diagnosed all patients in the study with conditions that were already known, including Huntington’s disease, fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies and motor neuron disease.

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.’

Such disorders are often difficult to diagnose due to the complex symptoms that patients present with, the challenging nature of the repetitive DNA sequences, and limitations of existing genetic testing methods.

In a statement Dr Cortese and Dr Houlden said: “Repeat expansions are a leading cause of neuromuscular and neurodegenerative disease. However, their genetic testing is often challenging and time consuming. The new method described represents a significant step forward in field of repeat expansion diseases and will hopefully enable to reach an early and accurate diagnosis in patients affected by this disabling group of conditions."

The study allows the team to begin validations to make the test available around the world.

The test works by scanning a patient’s genome using a technology called Nanopore sequencing. This technology 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.

Image: 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. (Credit: Garvan Institute of Medical Research)