It seems like Alzheimer’s and prion diseases like Kuru share a core molecular mechanism with misfolded proteins propagating and causing brain lesions. I find it really interesting that the gene protecting against Kuru has evolved naturally when according to Wikipedia, prion diseases don’t seem to have any effective treatments.
Cells have machinery for removing worn out proteins (tag em with ubiquitin and send them to incinerator [lysomes]). Doesn't surprise me too much a useful mutation (this folding is wrong detector) could work its way in.