Natural genetic variation gives complete resistance in prion diseases

Researchers at the Medical Research Council's Prion Unit at UCL have identified a naturally occurring variant of the human prion protein that produces resistance to prion diseases such as Creutzfeldt-Jakob disease (CJD). Prions are infectious agents that cause invariably fatal brain diseases such as CJD in humans, scrapie in sheep and BSE (bovine spongiform encephalopathy or 'mad cow disease') in cattle. They are a rare but important cause of dementia and it is increasingly recognised that the fundamental process involved in these diseases - prion proteins changing shape and sticking together to form fibres or polymers that damage the brain - is also what happens in the much more common dementias such as Alzheimer's disease, Parkinson's disease and other neurodegenerative diseases. Over many years, the MRC Prion Unit at the UCL Institute of Neurology has studied a prion disease called kuru which at one time was widespread in a remote area of the Papua New Guinea highlands. Kuru is caused by the same strains of prions that cause CJD and was spread in a community - the Fore - who used to consume their dead as a mark of respect at mortuary feasts. This led to a major epidemic of this prion disease which, at its height in the late 1950's, caused the death of up to 2% of the population each year. One of the studies the MRC Unit was performing, in collaboration with colleagues at the Papua New Guinea Institute for Medical Research, was to identify people from the worst affected area who had been exposed to kuru but had survived many years after the last mortuary feasts occurred in the late 1950's.