Creutzfeldt-Jakob disease: a protein disease.

Creutzfeld-Jakob disease (CJD) is essentially a protein disease. All forms of CJD are characterized by the deposition of an abnormal coformation of a normal cellular protein. This protein (PrPc) is encoded for by the PRNP gene on chromosome 20 in humans. There are important genetic influences on susceptibility to CJD and on the resulting clinico-pathological picture. The abnormal protein (PrPSc), may be the infectious agent itself or the main component of it. However, its precise role in the pathogenesis of disease is not clear. The detection of PrPSc plays a crucial role in the diagnosis of CJD and its electrophoretic characteristics are used to classify different forms of CJD. However, the "molecular diagnosis" of CJD is not without uncertainties.