NEUROOPHTHALMOLOGICAL ASPECTS OF PRION DISEASES

Prion brain diseases (Kuru, Creutzfeldt-Jakob disease, familial fatal insomnia (FFI), Gerstman-Straussler-Scheinker syndrome) are conditione d by the host's genome. Susceptibility (hereditary) is related to the PrPc gene polymorphism (insertion and/or point mutations at different codons). The normal harmless PrPc (neuron) is transformed into a rogue structurally altered PrPsc (scrapie) invading neurocells. Human consu mption of protein from bovine spongiform encephalopathy (BSE) cattle, fed scrapie-sheep offal, may be responsible for prion disease. The cli nical features are mirrored by a wide spectrum of brain grey matter in volvement in middle-aged patients. Progressive dementia and supranucle ar (ocular) motor symptoms are characteristic; at onset visual symptom s may occur in 20-25% Of cases. In dementing patients, diagnosis of pr ion disease may only be confirmed by brain biopsy, demonstrating the t ypical spongiosis and pleated prion plaques (meth-acarn fixation). Car e should be taken to never use tissue from dementing patients for subs titutive therapy or transplants.