Variants in the prion protein gene appear to give some protection against prion disease, Nature News reports.
In 2009, researchers from the University College London Institute of Neurology reported that during a kuru — an acquired prion disease — epidemic in Papua New Guinea, a novel PrP variant, G127V, was under positive evolutionary selection and seemed to confer protection against the disease, even in a heterozygous state.
When misfolded, prion proteins become transmissible agents that cause lethal neurodegenerative disease. Kuru, a mammalian prion disease, was first described in the mid-twentieth century among the Fore people of Papua New Guinea and its incidence was linked to ritual cannibalism, Nature News notes. Another prion disease, Creutzfeldt–Jakob, has sporadic, inherited, and acquired forms.
But some people appeared to be less susceptible to the disease.
The UCL team now reports in Nature that another variant — M129V — seems to give even greater protection against the disease. Mice expressing both the variant and wild-type human PrP are resistant to kuru and Creutzfeldt–Jakob disease prions, but were susceptible to variant CJD prions. Mice expressing only variant PrP V127 were resistant to all prion strains, the researchers report.
This variant, the researchers add, appears to prevent prion proteins from misfolding.
"It is a surprise," Eric Minikel from the Broad Institute tells Nature News. "This was a story I didn't expect to have another chapter."