In AD, CHI3L1 exhibited positive correlations with MMP9 (r = 0.663; q < 0.0001; CI 0.41 to 0.82), IL1B (r = 0.480; q = 0.007; CI 0.17 to 0.71), TNF (r = 0.395; q = 0.024; CI 0.06 to 0.65) and LRP1 (r = 0.745; q < 0.0001; CI 0.54 to 0.87). The gene discussed is MMP9; the disease is Alzheimer disease.