Abstract
Marmosets inoculated intracerebrally with brain tissue from a woman with Gerstmann-Straussler syndrome (an autosomal dominant dementia associated with spongiform change and amyloid deposition) developed an encephalopathy indistinguishable from that seen in marmosets inoculated with brain tissue from a typical case of Creutzfeldt-Jakob disease. As in Huntington's disease, in the pedigree of the patient with Gerstmann-Straussler syndrome women who subsequently developed the illness had increased fecundity. The pathogen in human transmissible dementia may arise from a sequence (which itself sometimes confers a selective advantage) located within the human genome.