A blood miRNA signature associates with sporadic Creutzfeldt-Jakob disease diagnosis

Sporadic Creutzfeldt-Jakob disease (sCJD) presents as a rapidly progressive dementia which is usually fatal within six months. No clinical blood tests are currently available for diagnosis or disease monitoring. Here, we profiled blood microRNA (miRNA) expression in sCJD. Small RNA-sequencing of 57 sCJD patients and 48 healthy controls revealed differential expression of hsa-let-7i-5p, hsa-miR-16-5p, hsa-miR-93-5p and hsa-miR-106b-3p. Downregulation of hsa-let-7i-5p, hsa-miR-16-5p and hsa-miR-93-5p replicated in an independent cohort using quantitative PCR, with concomitant upregulation of four of their mRNA targets. Absence of correlation in cross-sectional analysis with clinical phenotypes paralleled the lack of association between rate of decline in miRNA expression and rate of disease progression in a longitudinal cohort of 50 samples from 21 sCJD patients. Finally, the miRNA signature showed a high level of accuracy in discriminating sCJD from Alzheimer’s disease (AD). These findings highlight novel molecular alterations in the periphery in sCJD which can provide information about differential diagnosis and improve mechanistic understanding of human prion diseases.