CHI3L1 and Alzheimer disease: Two DEPs, ‘SPARC-related modular calcium-binding protein 1’ (SMOC1) and ‘chitinase-3 like-protein-1’ (CHI3L1, also known as YKL-40), both well-established markers of Alzheimer's disease,33,34 were found across 14 studies constituting the highest overlap among all studies (Supplementary Table 3).