Answer: Fatal familial insomnia (FFI) is a genetically inherited rare sleep disorder caused by a mutation in the prion protein PrPC.
Occasional disturbances in sleep, either difficulty falling asleep or difficulty remaining asleep, are normal. This is broadly referred to as insomnia. Insomnia may start to affect daytime performance and may result in excessive daytime sleepiness. For the average person, insomnia may be caused by stress or anxiety, resulting in excessive sympathetic nervous system activity.
However, one extremely rare form of insomnia is called “fatal familial insomnia” or FFI. In fatal familial insomnia, a patient may experience a progressively worsening inability to sleep. The age of onset of FFI varies greatly, with the average age of onset close to late-middle age (40 to 50 years old.) Usually, the disease is lethal within two years after presentation of symptoms.
In FFI, the person initially experiences insomnia and paranoia. Four or five months after, visual and auditory hallucinations begin, which may further worsen the insomnia. A complete inability to sleep is next, followed by a catatonic state.
Post mortem analysis of the FFI brain reveals that a mutation in PrPC protein is observed in the disease. This prion disease causes destruction of neurons in the brain, particularly in the thalamus and the inferior olives of the medulla.
As of now, there is no known cure for the disease. Because it has a strong genetic component associated with it, it can be tested for in the potential parents before they decide to have children.