Patients with NDs had also higher levels of CSF YKL-40 than controls (prion disease vs. controls p < 0.001, AD vs. controls p < 0.001, FTD vs. controls p = 0.001), with subjects with prion disease reaching the highest median levels (prion disease vs. AD p = 0.031, prion disease vs. FTD p < 0.001), while AD and FTD showed comparable concentrations of the biomarker (Table 2, Fig. 1c); these findings were confirmed after age and sex adjustment (Additional file 1: Table S3). The gene discussed is CHI3L1; the disease is Alzheimer disease.