Genotyping of the prion protein gene at codon 129

Sporadic, iatrogenic and new variant forms of Creutzfeldt-Jakob disease are associated with a predisposition for disease depending on a homozygosity at amino acid residue 129 of the prion protein gene (PRNP). A novel polymerase chain reaction/restriction digestion assay to screen for this polymorphism was developed and proved after comparison with a previously used method to be advantageous. Furthermore, for prevention of incorrect results an internal control for the restriction digestion was constructed. The feasibility of this method was tested in a cohort of 300 healthy Caucasian subjects. Of this normal population, 48.7% were heterozygous at codon 129, 43% homozygous for methionine and 8.3% for valine.