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Fatal familial insomnia (FFI) is a very rare autosomal dominant inherited prion disease of the brain. It is almost always caused by a mutation to the protein PrPC, 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, and confusional states like that of dementia. The average survival span for patients diagnosed with FFI after the onset of symptoms is 18 months.〔 The mutated protein, called PrPSc, has been found in just 29 families worldwide, affecting about 78 people; if only one parent has the gene, the offspring have a 45% risk of inheriting it and developing the disease. With onset usually around middle age, it is essential that a potential patient is 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 the year 1765.〔(The Family That Couldn't Sleep ).〕 ==Presentation== The age of onset is variable, ranging from 18 to 60, with an average of 50. The disease can be detected prior to onset by genetic testing. Death usually occurs between 7 and 36 months from onset. The presentation of the disease varies considerably from person to person, even among patients from within the same family. The disease has four stages: # The person has increasing insomnia, resulting in panic attacks, paranoia, and phobias. This stage lasts for about four months. # Hallucinations and panic attacks become noticeable, continuing for about five months. # Complete inability to sleep is followed by rapid loss of weight. This lasts for about three months. # Dementia, during which the patient becomes unresponsive or mute over the course of six months. This is the final progression of the disease, after which death follows. Other symptoms include profuse sweating, pinpoint pupils, the sudden entrance into menopause for women and impotence for men, neck stiffness, and elevation of blood pressure and heart rate. Constipation is common as well. As the disease progresses, the patient is forever stuck in a state of pre-sleep limbo. During these stages it is common for patients to repeatedly move their limbs as if dreaming. The first modern case was reported in the Netherlands of a 57-year-old man of Egyptian descent.〔 The man came in with symptoms of double vision and progressive memory loss, and his family also noted he had recently become disoriented, paranoid and confused. While he tended to fall asleep during random daily activities, he experienced vivid dreams and random muscular jerks during normal slow wave sleep.〔 After 4 months of these symptoms, he started having convulsions in the hands, trunk, and lower limbs while awake. The patient died at 58 (7 months after the onset of symptoms). An autopsy was completed post-mortem which revealed mild atrophy of the frontal cortex and moderate atrophy of the thalamus. The atrophy of the thalamus is one of the most common signs of fatal familial insomnia. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fatal familial insomnia」の詳細全文を読む スポンサード リンク
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