PRNP and variant Creutzfeldt-Jakob disease: A third national survey (the Appendix-3 Study) was therefore designed to test the hypothesis that there would be an absence of samples positive for abnormal PrP in appendices removed from people from outside the population considered most at-risk of acquiring vCJD from BSE via the food chain, i.e. appendices collected from operations performed either before 1980 (“historical”), or after 2000 in those born since 1996 (“new”).