People with a rare condition often have an error in their DNA that causes the disease. Doctors therefore map their DNA with a technique called sequence analysis. They use smart software to search for genes with a flaw. One third of patients receive a diagnosis. If that doesn’t work, the advice is: come back in a few years.
Modern techniques
“Only half of the patients follow this advice and go to the hospital again,” says PhD candidate Gaby Schobers of the Genetics Department of Radboudumc. “That’s a shame, because we conducted a study that shows that a few years later, thanks to modern techniques, we can increase the number of diagnoses from a third to 53 percent.”
Rapid developments
Together with pediatric neurologist Jolanda Schieving, Schobers followed 150 children with neurological disorders, such as epilepsy. Schobers: “After the first test, 47 children received a diagnosis immediately. We looked at all the others again up to five years after the test. Half reported themselves as advised, the other half received a call. We performed a new analysis on the old DNA measurements. If we still didn’t find anything, we mapped the DNA again. So a total of 32 patients were still diagnosed.”
The researchers found more genetic errors because the developments in genetics are moving at lightning speed. “We had already found some genes before, but only in recent years have been linked to a certain condition,” explains Lisenka Vissers, professor of translational genomics. “In addition, new software detects more errors. The technique of sequence analysis has also been further developed. Thanks to better chemicals, we can now visualize difficult-to-reach pieces of DNA.”
Finally clarity
Although the diagnosis is not made until years later for some patients, it is still very valuable. “There are medical reasons for this. A diagnosis clarifies what is causing the patient’s problems and may provide options for treatment and support,” says Schieving. “But clarity is also nice for the patient. We often receive very grateful reactions from parents of children who, after years of searching, hear the cause of a condition.”
In the absence of a diagnosis, the researchers advise to raise the alarm again in time. Schieving: “We then look at the patient again. Sometimes there are new indications for a certain condition. After that, thanks to a new analysis or DNA test, you may be able to determine a cause.” And what do we do with the half that still does not receive a diagnosis? Vissers: “We are now testing a more extensive analysis, in which we not only look at the genes, but also at the intervening DNA. Hopefully, we will soon find even more causes of disorders.”
By: National Care Guide
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