Supplementary Material for: Cerebrospinal Fluid Biomarker-Based Diagnosis of Sporadic Creutzfeldt-Jakob Disease: A Validation Study for Previously Established Cutoffs

Background: Several biomarkers have been proposed to
discriminate sporadic Creutzfeldt-Jakob disease (sCJD) from other
dementias and control cases. However, their clinical accuracy depends on
the PRNP codon 129 genotype, leaving it unclear how well established
markers behave in untested conditions. Methods: We
analyzed 14-3-3, tau, p-tau levels, and the p-tau/tau ratio in a
population sample collected from Polish hospitals including nondementia,
dementia, and definite sCJD cases and validated their parameters
according to previously established cutoffs. Additionally, the
correlation between biomarkers and disease duration as well as the
influence of the PRNP129 polymorphism are reported. Results: The tau levels and p-tau/tau ratios differed considerably between sCJD and clinically characterized non-CJD cases (p < 0.001). p-tau was only elevated in sCJD when compared to cases without dementia (p
< 0.05). Tau and the p-tau/tau ratio showed a sensitivity of 95 and
100%, respectively, in detecting sCJD cases. A negative correlation
between tau levels and disease duration, but not the timing of lumbar
puncture was observed. Conclusion: The present findings
confirmed the value of the p-tau/tau ratio as a robust sCJD biomarker
and suggest a role for tau as prognostic marker.