Application of “omics” to prion biomarker discovery

Abstract

Prion diseases, or Transmissible Spongiform Encephalopathies (TSEs), are invariably fatal neurodegenerative diseases associated with the conversion of the normal host cellular prion protein (PrPC) into the abnormal protease-resistant isoform (PrPSc) [1]. They occur in a wide range of host species including humans, the most common of which is sporadic CJD (sCJD), occurring at a rate of approximately 1 case per million a year worldwide and accounts for greater than 80% of CJD cases [2]. Amino acid changes, which include point or insertional mutations in the normal (cellular) prion protein (PrPC) encoded by the PRNP gene, are linked to genetic prion diseases such as Gerstmann-Strausler-Sheinker (GSS) disease, fatal familial insomnia (FFI), and genetically associated CreutzfeldtJakob disease (CJD). Acquired forms of disease are caused by ingestion of, or exposure to, contaminated biological material via food or during medical procedures. Kuru, found amongst the Fore tribe in Papua-New Guinea, was the first known human transmissible spongiform encephalopathy and resulted from exposure to infected material during ritualistic cannibalism. More recently a new human prion disease has emerged, variant CJD (vCJD), which is associated with exposure to the BSE agent in beef. Cases of iatrogenic transmission have also occurred through the use of improperly sterilized surgical instruments, the use of human growth hormone derived from cadaveric pituitaries, and transplantation of corneas and dura mater from infected patients [3]. Recently, human-to-human transmission of vCJD has been reported through blood transfusion [4]; human-adapted prions are more readily transmitted from human to human via this route than via ingestion of BSE prions from contaminated meat products [5].