Dutch hospitals pioneer large-scale, clinical use of new genetic test for rare diseases

Radboudumc and Maastricht UMC+ are the first hospitals in the world to use a new genetic test to diagnose rare diseases on a large scale and in clinical practice, the hospitals announced on Monday. The new genetic test can diagnose rare conditions more quickly and efficiently, and can replace around 15 other tests.

Healthcare providers worldwide already look for genetic causes for rare conditions in patients’ DNA. The new test is based on long-read genome sequencing, which maps the entire DNA of a patient by measuring small fragments of DNA and piecing them together.

According to Radboudumc, research has shown that this technique maps DNA much more completely than the currently used method of using short fragments. Like looking at a jigsaw puzzle, the picture becomes much clearer if the pieces are longer, the hospital said.

“For some rare diseases, this leads to over 10 percent more diagnoses,” said Alexander Hoischen, a Professor of Genomic Technologies at Radboudumc. “Additionally, with this fully measured DNA, we can discover new hereditary causes for certain conditions. This could increase the percentage of additional diagnoses through research to as much as 15 percent.”

The test also detects genetic errors that are hard to find, not only visualizing the building blocks of the DNA but also various modifications to the DNA that can provide new information about a condition.

According to the researchers, the new test will provide patients with a diagnosis more frequently and more quickly, effectively replacing around 15 other tests. “And that’s very important,” said Wendy van Zelst-Stams, a Professor of Care for Rare Diseases and head of the Genetics Department at both Radboudumc and Maastricht UMC+. “A diagnosis brings clarity and ends a long search. It often also provides a prognosis. People can connect with others in similar situations. For parents, it can relieve feelings of guilt. And we can assess risks if parents are considering having children.”

The hospitals are starting with 5,000 of these new genetic tests per year, initially looking at genetic forms of blindness and severe intellectual disabilities, but are hoping to expand their use soon. “I expect this will become the new standard for genome diagnostics and the only test we’ll perform in the future,” said Hoischen.