A new DNA test provides a more complete picture of genetic material than current standard diagnostics and leads to diagnoses more often, researchers from Radboud university medical center announced on June 13. The test can replace fifteen other tests, making the process faster and more efficient. Researchers recommend in the New England Journal of Medicine that this test be adopted globally as the first choice for diagnosing rare genetic disorders.
A condition is considered rare if it affects fewer than one in two thousand people. Despite this definition, up to 400 million people worldwide have a rare disease due to there being over seven thousand different types. Eighty percent of these conditions have a genetic cause. Obtaining a diagnosis often takes years, but it is important because it provides clarity, insight into future health prospects, opportunities for contact with others facing similar challenges, and information about risks when planning children.
Researchers from Radboudumc and Maastricht UMC+ collaborated to increase diagnostic rates for genetic disorders by comparing current standard diagnostics—which often involve multiple tests—with the new DNA test in one thousand patients. Professor of Translational Genomics Lisenka Vissers said, 'We showed that the new test yields three percent more diagnoses. It can also replace fifteen other tests. We recommend using this test worldwide as the first choice.'
The new approach uses long-read genome sequencing technology. In traditional methods, doctors examine DNA fragments about three hundred building blocks long before assembling them into a full sequence; the new method reads segments up to twenty thousand building blocks at once. This makes assembling the overall sequence easier and results in a clearer picture of an individual's DNA.
Additionally, this technique reads not only the basic building blocks but also modifications on the outside of DNA—modifications that can switch genes on or off and sometimes cause rare disorders.
Professor of Genomic Technologies Alexander Hoischen said, 'Thanks to long reads, we obtain an even more complete view of DNA and can detect complex and hard-to-find abnormalities. We then link these to specific conditions. In this way, our knowledge grows and we can make more diagnoses.' Long-read sequencing was also used at a recent Undiagnosed Hackathon in Nijmegen where nearly 150 specialists worked together to diagnose 33 families; five new diagnoses were made using detailed mapping from this method.
