Blood test helps with rapid diagnosis of rare genetic diseases

A blood test has been developed that can rapidly diagnose thousands of rare genetic diseases in babies and children suspected of having a rare disease.

Rare genetic diseases can often take years to be diagnosed, suggesting a need for faster detection methods. Researchers in Melbourne, Australia, have developed a diagnostic test that analyses thousands of proteins in blood samples to identify any protein variants that may be disease-causing. Their study, published in Genome Medicine, shows that the test can rapidly identify more than 8000 proteins and can be used to diagnose half of all known rare genetic diseases.

'By providing patients and their families with a rapid clinical diagnosis, the patient has a greater chance at survival as they can begin treatment far sooner, if available,' explained Professor David Thorburn from the Murdoch Children's Research Institute and joint corresponding author. '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.'

Genome sequencing is increasingly used as a tool to diagnose both genetic and infectious diseases (see BioNews 1163, 1265 and 1204). However, for 50 percent of patients, further tests are needed in addition to genome sequencing in order to reach a diagnosis. The study of certain aspects of proteins, known as proteomics, enables researchers to gain a better insight into the function of the genome variants that encode these proteins.

'If our blood test can provide clinical diagnoses for even half of the 50 percent 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,' said Dr David Stroud from the University of Melbourne and joint corresponding author.

In results presented at the European Society of Human Genetics' annual conference in Milan, Italy, it was shown that by examining blood samples from the child and from both parents, researchers can better identify differences between people affected by a genetic disease and unaffected carriers of the disease.

The study focuses on a set of more than 300 rare genetic diseases which involve problems with the mitochondria, the site of energy production in our cells. These diseases are often difficult to diagnose due to the variation in associated clinical symptoms, which can affect one or many organs. The new blood test was able to identify disease-causing protein variants in 83 percent of patients, outperforming the standard enzyme test currently used for diagnosing such mitochondrial diseases.

While these initial results are promising, further validation is needed to assess the blood test's broader applications. Researchers are currently recruiting 300 patients with a range of rare genetic diseases, with the hope the test can eventually be used in clinical genetics services in Victoria, Australia.

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The availability of genetic and genomic testing for people and families affected by rare disease will be discussed at the free-to-attend online event Rare Disease Genomic Testing: How Do We Make Access Equitable and Timely?, taking place online on Wednesday 22 October 2025.

Find out more and register here.