04/04/2026
Fatal familial insomnia (FFI) is a rare and fatal genetic prion disease that typically has an onset around middle age (40s or 50s) and progresses rapidly, with a median survival time of 18 months. It’s caused by a mutation in the PRNP gene, which causes misfolded proteins to destroy neurons in the thalamus, the brain’s sleep controller. It typically presents with worsening refractory insomnia as the initial symptom accompanied by autonomic dysfunction such as sweating, constipation, tachycardia, and hypertension. As the disease progresses, neurological and psychiatric symptoms emerge, including cognitive decline, apathy, involuntary movements, dysarthria, and disturbances in voluntary movement. It must be differentiated from Alzheimer’s disease and Creutzfeldt-Jakob disease, as each can present with rapidly progressing dementia. Definitive diagnosis during life requires genetic testing. Treatment is supportive, as there is no cure.
FFI affects 1-2 out of 1 million people. While typically passed down from one parent, rarely, spontaneous cases of a new mutation do occur that can also be passed down.
Will you ever use this information? Probably not. But if I had to learn it this week, so did you.
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📚: PMID: 39716111
📚: PMID: 39660573
📚: Clevelandclinic.org, “Fatal Familial Insomnia”
