According to the mode of transmission, CJD is classified into three forms: sporadic (sCJD), which is the most common, accounting for 85–90% of cases; genetic, accounting for 15% of cases, due to autosomal-dominant mutations in the prion protein gene (PRNP); and acquired, accounting for less than 1% of cases resulting from prion transmission by an external source, such as the human exposure to bovine spongiform encephalopathy (BSE) during the late 1980s and early 1990s [66]. This evidence concerns the gene PRNP and Creutzfeldt Jacob disease.