While various biomarkers, such as nitric oxide synthase 2 (NOS2/iNOS), human beta-defensin-2 (hBD-2), matrix metalloproteinase 8/9 (MMP8/9), and fatty acid-binding protein 5 (FABP5), have been proposed for predicting AD endotypes (14), they have proven insufficient for personalized medicine. The gene discussed is MMP8; the disease is Alzheimer disease.