The identification of vCJD in a PRNP codon 129 MV individual was not unexpected because earlier experimental evidence from humanised transgenic mouse models, expressing physiological levels of the human prion protein, indicated that other PRNP codon 129 genotypes are susceptible to infection with the BSE agent but may be subject to more prolonged incubation periods [53]. This evidence concerns the gene PRNP and variant Creutzfeldt-Jakob disease.