Fatal familial insomnia (FFI) is a rare, inherited neurodegenerative disorder caused by a mutation in the PRNP gene. Characterized by progressive insomnia, memory loss, and other neurological symptoms, FFI typically leads to death within 9 to 30 months of symptom onset. Currently, there is no cure; treatment focuses on symptom management. Research is ongoing to find effective treatments, including a clinical trial testing the antibiotic doxycycline.