We and others have shown that mice devoid of PrPC (Prnp0/0) are resistant to prion infections, neither developing disease nor propagating prions in the brains after intracerebral inoculation with the prions [20,21,22,23], confirming that the conversion of PrPC into PrPSc eventually leading to accumulation of PrPSc in the brain is a key pathogenic event in prion diseases. The gene discussed is PRNP; the disease is prion disease.