Our diagnostic composite panel included four biomarkers corresponding to Aβ transport and ablation (sLRP1 and GSN) [14, 25], cell apoptosis (Caspase 3), as well as the novel potential biological processes (KLK4), which we hope will provide valuable diagnostic strategies for AD, while shedding new light on the pathogenesis and disease progression of AD. This evidence concerns the gene KLK4 and Alzheimer disease.