Work

Value of positive RT-QuIC replicate number in sporadic Creutzfeldt-Jakob disease

Year: 2026

Type: article

Abstract: Background: Real-time quaking-induced conversion (RT-QuIC) of recombinant prion protein is a biomarker for Creutzfeldt-Jakob disease (CJD). RT-QuIC assesses a sample's seeding activity across multiple wells. We aim to model the test within a binomial framework and describe possible applications. Methods: This is a single-centre retrospective observational study. CJD and non-CJD cases with cerebrospinal fluid RT-QuIC were enrolled (2014-2018). The probability of a positive event in one well (θ+) for each group was assessed. θ+ can be used to calculate the posterior probability of disease (P_post) or as input parameters for computer simulations. Results: Data from 584 sporadic CJD (sCJD) and 226 non-CJD cases were used. Respectively, θ+ was 0.841 (95% CI 0.823 to 0.857) and 0.025 (95% CI 0.016 to 0.040). The distribution of RT-QuIC results did not differ between all sCJD samples and definite sCJD cases and across groups with different alleles at codon 129 of the PRNP gene. P_post was calculated for each result. The distribution of results did not differ significantly across years in def/prob-sCJD and non-CJD. Discussion: RT-QuIC results distribution and θ+ may be used for intra-laboratory quality control and P_post determination. Future studies should explore the utility of θ+ to increase diagnostic accuracy and inter-laboratory comparison.

Source: BMJ Neurology Open

DOI: 10.1136/bmjno-2026-001863