Blood test rapidly diagnoses rare genetic diseases in children

Researchers at The University of Melbourne and Murdoch Children’s Research Institute (MCRI) say they have developed a blood test capable of rapidly diagnosing rare genetic diseases in babies and children, thus eliminating the need for costly and invasive procedures, giving families earlier access to treatment. The team’s work has been published in the journal Genome Medicine.

Genome sequencing has significantly advanced the diagnosis of rare diseases; however, this is only successful for half of all cases. The remaining half of patients must undergo additional functional tests to confirm if a gene mutation is causing the disease — a diagnostic process that can take months or years with no guarantee of a result, as most functional tests are only applicable to a single or handful of rare diseases.

“A disease is rare if it affects fewer than one in 2000 people, and there are more than 7000 different rare diseases, most of which have a genetic origin,” noted by The University of Melbourne’s Associate Professor David Stroud.

The new blood test can rapidly detect abnormalities in up to 50% of all known rare genetic diseases in a matter of days by analysing the pathogenicity of thousands of gene mutations at once, potentially replacing thousands of other functional tests. MCRI’s Professor David Thorburn noted that a rapid clinical diagnosis gives the patient a greater chance at survival as they can begin treatment sooner.

“Even in cases where a child has died from an undiagnosed genetic disease, this new test can be carried out on tissue samples to determine the genetic mutation responsible for their death,” Thorburn said. “Such diagnoses not only provide closure to families, but this information can also be used in IVF to help the parents to have future children who have not inherited the life-threatening disease.”

The research team benchmarked their test against an existing clinically accredited enzyme test offered by Victorian Clinical Genetics Services at MCRI, focusing on mitochondrial diseases. The team found their new test is more effective in confirming a mitochondrial disease diagnosis as it is much more sensitive and accurate and can produce faster results.

“A recent health economics analysis in collaboration with the Melbourne School of Population and Global Health showed that our test could be offered at a similar cost to the enzyme test that is currently offered clinically for mitochondrial diseases, but our test is much more cost-effective as it can test for thousands of different genetic diseases, whereas other functional tests are mostly targeted to a small number of genetic disorders,” said The University of Melbourne’s Dr Daniella Hock.

Stroud added, “If our blood test can provide clinical diagnoses for even half of the 50% of patients who don’t get a diagnosis through genome sequencing, that’s a significant outcome as it means those patients don’t have to undergo unnecessary and invasive testing such as muscle biopsies, which for a baby requires general anaesthetic, and that doesn’t come without risks.”

Hock said the researchers are now in the process of recruiting 300 patients with a range of different genetic disorders to participate in a study to investigate the broad utility of their diagnostic test. It is anticipated that the test will eventually be offered as a diagnostic service at Victorian Clinical Genetic Services.

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