In terms of diagnostic value, we confirmed that only YKL-40 demonstrates a moderate accuracy with ≥ 80% sensitivity and specificity in discriminating between controls and AD or prion disease [19, 57], while neither YKL-40 nor CHIT1 or GFAP has a significant diagnostic value in any other comparison [18, 20, 57]. The gene discussed is CHI3L1; the disease is prion disease.