PRNP and prion disease: To study the influence of the PRNP codon 129 MV polymorphism on MDH1-levels in CSF, we stratified our genetic prion disease cohort according to the PRNP codon 129 genotype in gCJD (E200K MM and MV, V210I MM and MV, as well as FFI-D178N MM and MV).