<Tr> <Th> Specialty </Th> <Td> Sleep medicine </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Fatal familial insomnia (FFI) is an extremely rare autosomal dominant inherited prion disease of the brain . It is almost always caused by a mutation to the protein PrP, but can also develop spontaneously in patients with a non-inherited mutation variant called sporadic fatal insomnia (sFI). FFI has no known cure and involves progressively worsening insomnia, which leads to hallucinations, delirium, confusional states like that of dementia, and eventually, death . The average survival time for patients diagnosed with FFI after the onset of symptoms is 18 months . </P> <P> The mutated protein, called PrP, has been found in just 40 families worldwide, affecting about 100 people; if only one parent has the gene, the offspring have a 50% risk of inheriting it and developing the disease . With onset usually around middle age, it is essential that a potential patient be tested if they wish to avoid passing FFI on to their children . The first recorded case was an Italian man, who died in Venice in 1765 . </P>

What is the disease that makes you not sleep