PRNP(prion protein), also known as CD230 and PRP, is a protein that in humans is encoded by the PRNP gene. The major prion protein is expressed in the brain and several other tissues. Expression is most predominant in the nervous system but occurs in many other tissues throughout the body. Puckett et al. (1991)identified a RFLP with a high degree of heterozygosity in the 5-prime region of the PRNP gene, which might serve as a useful marker for the pter-p12 region of chromosome 20.PRNP is associated with a variety of cognitive deficiencies and neurodegenerative diseases such as Creutzfeldt-Jakob disease, bovine spongiform encephalopathy, and kuru. PRNP is highly conserved through mammals, lending credence to application of conclusions from test animals such as mice. Comparison between primates is especially similar, ranging from 92.9-99.6% similarity in amino acid sequences.