A newly discovered biomarker -- visible in brain scans for hours after febrile seizures -- predicts which individuals will subsequently develop epilepsy, according to researchers. This diagnostic ability could lead to improved use of preventive therapies for the disorder. Up to 40 percent of children who have fever-related seizures lasting more than 30 minutes (known as febrile status epilepticus) will eventually develop epilepsy. However, it has not been possible to predict early on who will get the disorder, which can arise 10 or more years later.