Significantly decreased concentrations of Aβ1–42 (P < 0.001), Aβ1–40 (P = 0.018), as well as a lower Aβ ratio (P < 0.001), sAPPα (P < 0.001), and sAPPβ (P < 0.001) were found in AD patients compared with controls, while YKL-40 (P < 0.001) and hFABP (P < 0.001) were found to be increased in AD patients. The gene discussed is CHI3L1; the disease is Alzheimer disease.