September 27, 2024 by Boston University School of Medicine Genetic prion disease generally manifests with cognitive difficulties, poor muscle control and abrupt jerking movements of muscle groups and/or entire limbs. The three major phenotypes of genetic prion disease are genetic Creutzfeldt-Jakob disease (gCJD), fatal familial insomnia (FFI), and Gerstmann-Sträussler-Scheinker (GSS) syndrome. The most common cause...