Summary
Gerstmann-Straussler-Scheinker syndrome (GSSS) is a particular and rare form of human transmissible spongiform encephalopathy (TSE) due to a defective gene encoding the prion protein (PRNP gene) and marked by particular multicentric amyloid plaques in the brain. The codon 102 mutation is the most frequent, as it can be found in several European countries and in Japan. It causes the ataxic form of GSSS: cerebellar syndrome at onset, followed by oculomotor, pyramidal and intellectual signs. Death occurs anywhere between 1 and 11 years after onset. Amyloid plaques can be found mainly in the cerebellum. The codon 117 mutation has been described in 2 families (German and Alsacian); it causes dementia with pyramidal or pseudobulbar signs. Amyloid plaques are mono- or multicentric. Other mutations are uncommon: 198 (one American family), 217 (one Swedish family), 145 (one Japanese patient) and 105 (one case in Japan). The codon 198 and 217 mutations are particular in that multicentric plaques and neurofibrillar degeneration identical to those found in Alzheimer's disease are observed. The codon 145 mutation causes clinical symptoms similar to Alzheimer's disease; amyloid plaques are made of truncated PrP. The transmissible nature of the previously mentioned mutations has not yet been demonstrated. Finally the codon 105 mutation causes spastic paraparesia with late dementia. Amyloid plaques are predominant in the frontal lobe. GSSS may not actually be a TSE. To date, there is no treatment of the underlying pathological mechanisms of the disease. *Author: Dr J-P. Brandel (August 2004)*.
