From OMIM
Gerstmann-Straussler disease (GSD) is a rare inherited prion disease characterized by adult onset of memory loss, dementia, ataxia, and pathologic deposition of amyloid-like plaques in the brain (Gerstmann et al., 1936). GSD typically presents with progressive limb and truncal ataxia, dysarthria, and cognitive decline in the thirties and forties, and the average disease duration is 7 years. GSD can be distinguished from CJD by earlier age at onset, longer disease duration, and prominent cerebellar ataxia (Masters et al., 1981). On the basis of clinical and pathologic criteria, Hsiao et al. (1989) suggested that Gerstmann-Straussler syndrome could be classified into 3 forms: an 'ataxic' form, a 'dementing' form, and a dementing form that is accompanied by pathologic quantities of neurofibrillary tangles (NFTs). However, these distinctions may only underscore the phenotypic variability in presentation and progression of the disease (Panegyres et al., 2001). PRNP-related amyloid angiopathy is usually not a feature of CJD, GSD, or FFI. However, PRNP-immunoreactive amyloid deposits within the walls of cerebral vessels have been observed in patients with truncating mutations in the PRNP gene. Data suggest that C-terminal-truncated PRNP proteins lacking the glycosylphosphatidylinositol (GPI) anchor required to attach the protein to the plasma membrane may readily form amyloid fibrils that result in cerebrovascular amyloid deposition (summary by Revesz et al., 2009).  http://www.omim.org/entry/137440

From MedlinePlus Genetics
Prion disease represents a group of conditions that affect the nervous system in humans and animals. In people, these conditions impair brain function, causing changes in memory, personality, and behavior; a decline in intellectual function (dementia); and abnormal movements, particularly difficulty with coordinating movements (ataxia). The signs and symptoms of prion disease typically begin in adulthood and worsen with time, leading to death within a few months to several years.  https://medlineplus.gov/genetics/condition/prion-disease