PRNP and Creutzfeldt Jacob disease: Overall, these studies have been so far disappointing, but further genetic association studies in homogenous population, such as that of the Italo-Greek minority of the Calabrian cluster with high inbreeding coefficient [24], would need to be performed for investigating whether there are genes, other than PRNP, that may account for differences in age at onset in E200K CJD patients.