An update of the epidemiology of sporadic Creutzfeldt-Jakob disease in Italy based on neuropathologic and molecular typing of a large cohort of patients

Despite its proven heterogeneity, sporadic CJD (sCJD) to date has been only analyzed epidemiologically as a single entity. Taking advantage of the current high autopsy rate for clinically suspected CJD cases, we evaluated the frequency of sCJD subtypes in Italy in a large cohort of consecutive cases. Inclusion criteria were onset of symptoms within the period 2000 – 2005 and neuropathologic disease confirmation. Patients carrying pathogenic mutations in the coding region of PRNP and/or having a positive family history were excluded. PRNP genotyping was performed in 402 (87.9%) cases and showed 283 (70.4%) MM, 62 (15.4%) MVand 57 (14.2%) VV subjects. Most cases belonged to MM/MV1 (51%), mixed MM/MV1+2C (22%), VV2 (15%) and MV2 (8%) subtypes, while the remaining 4% comprised rare variants or atypical cases. Our study provides the first estimate of the incidence of the sCJD variants in a large cohort of consecutive patients and the basis for the study of spatial and temporal sCJD clustering in Italy.