Cerebral cavernous malformations 1 is a condition caused by a mutation in the KRIT1 gene. Cerebral cavernous malformations are collections of small blood vessels in the brain that are enlarged or irregular in structure. These vessels have very thin walls, which means they often leak and can cause health problems. Symptoms may include: headaches, paralysis, seizures, hearing or vision loss, memory loss, and bleeding in the brain (cerebral hemorrhage), which could result in death. Some people never have any health problems or symptoms. The severity of cerebral cavernous malformations depends on their location and the number present, both of which can change over time. This condition affects about 0.5 percent of the population worldwide. This condition can occur in individuals who have no family history of having it (sporadic), or can be passed from parents to children in an autosomal dominant pattern, meaning that if one of the parents has it, there is a 50% chance their child will have it too. CT scans, MRIs, and blood tests can be used to diagnose this condition. Treatment may include surgery to remove the affected blood vessels, or medication to control symptoms (for example, antiepileptic drugs for seizures).