Brain capillary damage using a novel CSF biomarker of BBB-associated capillary PEs, PDGFRβ, and regional BBB permeability were developed in the hippocampus of individuals with early cognitive decline independent of Aβ and tau pathology, suggesting that BBB damage is an early biomarker of human cognitive dysfunction, including the early stages of AD (Nation et al., 2019). The gene discussed is PDGFRB; the disease is Alzheimer disease.