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Cannibalism and prion disease John Collinge of University College London and his colleagues think prehistoric cannibalism may have been the source of genes protecting people against prion diseases [Science, 300, 640 (2003)]. These diseases result from misfolded prion proteins, which cause other prion proteins to misfold and clump together in the brain. The diseases include kuru and Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cows. They cause degeneration of the brain and, ultimately, death. Collinge and his coworkers say cannibalism is the most likely explanation for their finding that the protective genes have long been widespread worldwide. They found earlier that genetic mutations called M129V and E219K somehow protect people against Creutzfeldt-Jakob disease. From about 1920 to 1950 in Papua New Guinea, a kuru epidemic hit the Fore, whose kinship groups ate deceased relatives at mortuary feasts. (Australia banned cannibalism in the mid-1950s.) The scientists found that 23 of 30 women who had eaten in mortuary feasts were protected by the M129V mutation. The group has sequenced and analyzed the prion protein gene in more than 2,000 chromosome samples from people selected to represent worldwide genetic diversity. They found M129V or E219K in every population. Their data indicate that the variations are ancient--more than 500,000 years old, they estimate. According to Collinge, "There is extensive anthropological evidence that cannibalism is not just some rarity that happened in New Guinea." |
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