CHI3L1 and Alzheimer disease: However, several genes induced in astrocytes by tau and/or Aß pathology have been reported to have utility as potential fluid biomarkers for AD, Chil1’s 1:1 orthologue CHI3L1 (also known as YKL-40), and Icam1 are both induced in the MAPT301S mouse and are putative CSF/blood AD biomarkers66.