Crucial AD-associated genes were identified in each cell type, including RGS1, GRIA1, GRIA3, GRIA4, DLGAP1, MSN, CHL1, DCN, LPAR1, EGFR, GRM5, CAMK2A, APOE, AQP4, GFAP, and CD44, showing potential involvement in AD. The gene discussed is CHL1; the disease is Alzheimer disease.