Fatal Familial Insomnia (FFI) is an extremely rare inherited autosomal dominant disorder of brain — most often caused by a protein mutation passed on through families. But FFI can also develop spontaneously with a non-inherited mutation variant called Sporadic Fatal Insomnia (sFI).
FFI is clinically characterized by insomnia with/without a diurnal dreaming state, hallucinations, delirium and dysautonomia preceding motor and connective deterioration.
The average age of onset in FFI is 50 but can range from 18-60 years.
Worldwide there are only 40 families which have been found to carry the disease, affecting about 100 people altogether.