Sporadic Creutzfeldt-Jakob disease diagnostic accuracy is improved by a new CSF ELISA 14-3-3γ assay

- We quantified CSF 14-3-3γ in 72 sCJD and 73 Non-CJD patients, by a new ELISA assay.
- WB and ELISA 14-3-3γ results matched in 81% of all cases.
- WB inconclusive cases were further discriminated by ELISA 14-3-3γ assay.
- ELISA 14-3-3γ is the best single predictive marker for sCJD early diagnosis.
- PRNP genotype did not influence ELISA 14-3-3γ protein levels.

Protein 14-3-3 is a reliable marker of rapid neuronal damage, specifically increased in cerebrospinal fluid (CSF) of sporadic Creutzfeldt-Jakob disease (sCJD) patients. Its detection is usually performed by Western Blot (WB), prone to methodological issues. Our aim was to evaluate the diagnostic performance of a recently developed quantitative enzyme-linked immunosorbent (ELISA) assay for 14-3-3γ, in comparison with WB and other neurodegeneration markers. CSF samples from 145 patients with suspicion of prion disease, later classified as definite sCJD (n = 72) or Non-prion diseases (Non-CJD; n = 73) comprised our population. 14-3-3 protein was determined by WB and ELISA. Total Tau (t-Tau) and phosphorylated Tau (p-Tau) were also evaluated. Apolipoprotein E gene (ApoE) and prionic protein gene (PRNP) genotyping was assessed. ELISA 14-3-3γ levels were significantly increased in sCJD compared to Non-CJD patients (p < 0.001), showing very good accuracy (AUC = 0.982; sensitivity = 97%; specificity = 94%), and matching WB results in 81% of all cases. It strongly correlated with t-Tau and p-Tau (p < 0.0001), showing slightly higher specificity (14-3-3 WB - 63%; Tau - 90%; p-Tau/t-Tau ratio - 88%). From WB inconclusive results (n = 44), ELISA 14-3-3γ correctly classified 41 patients. Additionally, logistic regression analysis selected ELISA 14-3-3γ as the best single predictive marker for sCJD (overall accuracy = 93%). ApoE and PRNP genotypes did not influence ELISA 14-3-3γ levels. Despite specificity for 14-3-3γ isoform, ELISA results not only match WB evaluation but also help discrimination of inconclusive results. Our results therefore reinforce this assay as a single screening test, allowing higher sample throughput and unequivocal results.