PRNP and variant Creutzfeldt-Jakob disease: [9] This case was the first indication that individuals with PRNP genotypes other than MM could be infected by the vCJD agent. All three codon 129 genotypes are now thought to be susceptible to vCJD infection following the identification of two VV genotype appendix tissues positive for vCJD associated PrP (PrPSc) in an anonymous screening study, and the successful transmission of vCJD to ‘humanised’ transgenic mice of each genotype. [10]–[12]