Hence in vCJD, prions are believed to enter the nervous system by absorption through the gut following consumption of infected food, replication in the spleen, and neural entry via the spinal cord [14] whereas sporadic cases are less likely to have an iatrogenic aetiology, and to result from either random mutation or posttranslational modification of the PrP gene [3, 4]. The gene discussed is PRNP; the disease is variant Creutzfeldt-Jakob disease.