New long-read genetic testing identifies more rare conditions

The test provides more people with a diagnosis for rare conditions and is faster and more efficient than current diagnostic methods. It can also replace around 15 other tests, the hospital says.

“We’re starting with 5,000 tests per year, about one-sixth of the analyses we perform annually,” says Helger IJntema, head of the genome diagnostics laboratory. “Initially, we’ll use the test for genetic forms of blindness and severe intellectual disabilities.”

The new test is based on so-called long-read genome sequencing. If a condition is potentially hereditary, the entire DNA of a patient is mapped by measuring small fragments of DNA and piecing them together into longer bits.

Research has shown that this new technique maps DNA much more completely than the method using short fragments.

“This leads to over 10% more diagnoses for some diseases,” says genomic technologies professor Alexander Hoischen. “We can also discover new hereditary causes for certain conditions. This could increase the percentage of additional diagnoses through research to as much as 15%.”

Clinician Wendy van Zelst told BNR radio that the new approach will make a difference to many patients.

“Around a third of those with a rare disease get the wrong diagnoses,” she said. “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.”