Abstract: Fatal familial insomnia is a rare and fatal hereditary prion disease. The core clinical manifestations are sleeprelated symptoms, rapidly progressive dementia, autonomic nerve dysfunction and others. For the high fatality rate of this disease, its early diagnosis is particularly important. But, because its symptoms are rare and nonspecific, it is difficult for clinicians to identify FFI in early stage, which cause misdiagnosis rate and missed diagnosis rate. The pathogenesis, pathological changes, clinical features, auxiliary examination features and diagnostic criteria of FFI were described to improve the understanding of FFI among clinicians and  a new diagnostic criteria for Chinese population was put forward.

Key words: insomnia, fatal familial, dementia, PRNP gene