When doctors perform brain surgery to treat epilepsy, they sometimes find structural changes in the brain's development. For a long time, standard genetic tests have struggled to see the full picture of these mutations. Now, a new method called Optical Genome Mapping (OGM) is showing promise in finding much more detail.
In a small study of four patients, researchers used OGM to look at surgically removed brain tissue. They found that this tool can spot large and complex mutations—specifically mosaic structural variants—that traditional sequencing missed. These are mutations that only exist in a subset of cells, making them incredibly hard to track down.
In one specific case, the tool even pinpointed a hidden deletion in a gene called DEPDC5. The researchers discovered that this deletion happened because two pieces of DNA, known as Alu elements, essentially swapped places. This level of detail helps explain exactly how these genetic errors occur.
While these results are exciting, the technology is still in its early stages. To work well, OGM needs very high-quality DNA from clinical samples. It is currently being used as a powerful extra tool to help doctors better understand the genetic roots of neurological disorders.