[Inherited human prion diseases].

Familial prion diseases (familial Creutzfeldt-Jakob disease: Gerstmann-Sträussler-Scheinker disease, Fatal familial insomnia) are rare, but are also at present one of the most fascinating chapters of Neurology because of their double transmissibility. They are hereditary diseases of adults with a dominant autosomal transmission and an almost complete penetrance. They result most often of a point mutation of the gene of PrP with a consequent change in its primary sequence and conformation. Does the mutated PrP acquire a novel function or lose a still unknown function? At present there is no answer tho these question. The mutated PrP may sometimes be transmitted from man to animals. All PrP point mutations appear to have a noxious effect on neurons, but only some of them are transmissible. How mutated PrP acquires or does not acquire transmissibility may represent a fundamental progress in our understanding of prion diseases.