The E219K polymorphism, prevalent in Asian populations and associated with a partial resistance to sCJD, has been replicated in a knock-in mouse model, which demonstrated that the PrP 219K molecule is readily converted to PrPSc after challenge with vCJD and that the conversion occurs even more effectively than in the 219E molecule. The gene discussed is PRNP; the disease is variant Creutzfeldt-Jakob disease.