Dutch Hospitals Pioneer Large-Scale Use of New Genetic Test for Rare Diseases

Radboudumc and Maastricht UMC+ have become the first hospitals globally to implement a new genetic test for diagnosing rare diseases on a large scale, as announced on November 17, 2025. This innovative test utilizes long-read genome sequencing, which allows for a more comprehensive mapping of a patient's DNA by assembling longer fragments, thereby enhancing diagnostic accuracy. The hospitals aim to conduct 5,000 of these tests annually, initially focusing on genetic forms of blindness and severe intellectual disabilities.

Dutch hospitals pioneer large-scale, clinical use of new genetic test for rare diseasesNew long-read genetic testing identifies more rare conditions

The new genetic test is designed to replace approximately 15 existing diagnostic tests, streamlining the process for healthcare providers. According to Alexander Hoischen, a Professor of Genomic Technologies at Radboudumc, this method can lead to over 10% more diagnoses for certain rare diseases. Furthermore, it has the potential to identify new hereditary causes, which could increase the rate of additional diagnoses to as much as 15%. Helger IJntema, head of the genome diagnostics laboratory, emphasized that the test will significantly improve the speed and efficiency of diagnosing rare conditions.

New long-read genetic testing identifies more rare conditionsDutch hospitals pioneer large-scale, clinical use of new genetic test for rare diseases

Wendy van Zelst-Stams, a Professor of Care for Rare Diseases, highlighted the critical role of accurate diagnoses in patient care. She noted that a correct diagnosis not only provides clarity but also helps in establishing a prognosis, connecting patients with similar conditions, and alleviating parental guilt regarding hereditary diseases. The new test aims to reduce the incidence of misdiagnoses, which affects about one-third of patients with rare diseases, often leading to inappropriate treatments.

New long-read genetic testing identifies more rare conditions

The hospitals' leadership expressed optimism about the new testing method. Alexander Hoischen stated, “I expect this will become the new standard for genome diagnostics and the only test we’ll perform in the future.” This sentiment reflects a broader ambition to enhance diagnostic practices in the field of rare diseases.

New long-read genetic testing identifies more rare conditions

While the introduction of the new genetic test has been met with enthusiasm, some experts caution about the implications of widespread genetic testing. Concerns have been raised regarding the potential for overdiagnosis and the psychological impact of receiving genetic information that may not have immediate clinical relevance. Critics argue that the healthcare system must ensure adequate support and counseling for patients undergoing genetic testing.

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

As Radboudumc and Maastricht UMC+ begin the rollout of the new genetic test, the medical community will closely monitor its impact on patient outcomes and diagnostic accuracy. Future expansions of the test's application are anticipated, with hopes of addressing a broader range of rare genetic conditions.

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

• “For some rare diseases, this leads to over 10 percent more diagnoses,” — Alexander Hoischen, Professor of Genomic Technologies at Radboudumc

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

• “Around a third of those with a rare disease get the wrong diagnoses,” — Wendy van Zelst-Stams, Professor of Care for Rare Diseases

New long-read genetic testing identifies more rare conditions

• “And that often leads to the wrong treatment. This test allows us to make the right diagnosis more quickly and then put together a more appropriate treatment package.” — Wendy van Zelst-Stams, Professor of Care for Rare Diseases

New long-read genetic testing identifies more rare conditions