Human prion diseases.

Major advances have been made in prion diseases. Recent data indicate that the prion protein is likely to be a synaptic protein with a functional role in synaptic transmission. An impressive body of evidence suggests that (1) the normal prion protein plays a central role in prion replication; (2) the replication process implies an interaction between the normal prion protein and the pathogenic prion protein; and (3) the pathogenic prion protein is the infectious agent, the infectivity of which is dependent on its abnormal conformation. Genetic and protein analyses have expanded the spectrum of prion diseases and have underlined the complexity of genotype-phenotype interactions.