Researchers develop a blood test that diagnoses rare genetic diseases in days

Researchers at the University of Melbourne and the Murdoch Children’s Research Institute have created a blood test that can identify up to half of all known rare genetic diseases in babies and children within days. The advance could replace many costly, invasive procedures and shorten a diagnostic journey that often stretches into months or years.

Genome sequencing transformed rare-disease diagnostics, but still leaves about 50 percent of cases unresolved. The new assay bridges that gap by examining the pathogenic potential of thousands of gene variants simultaneously. In initial evaluations, it returned results fast enough to influence clinical decisions without the need for muscle biopsies or multiple single-disease functional tests.

Early and accurate diagnoses matter. Confirming a cause quickly lets clinicians deliver targeted treatments—when available—and prevents care teams from resorting to unnecessary, risky procedures on young patients. The test can also analyze stored tissue, helping families who have lost a child to an undiagnosed condition understand what happened and plan future pregnancies with clearer information.

The developers benchmarked their method against the accredited enzyme assay currently used for mitochondrial disorders, a severe class of diseases that sap cellular energy and can lead to organ failure. The blood test proved more sensitive and delivered results sooner, all at a similar per-patient cost.

A health economics analysis suggests the new approach is more cost-effective overall because it screens for thousands of conditions in one run. Backed by a ~$1.95 million federal grant, the team is enrolling 300 patients across a range of genetic disorders to validate the test further. If upcoming data are positive, the assay is expected to become a diagnostic service at Victorian Clinical Genetics Services.