These types of HDLs play a protective role in AD progression in the brain by (1) intervening in Aβ production by binding to amyloid precursor protein and inhibiting its endocytic processes, (2) inhibiting Aβ aggregation by blocking Aβ self-assembly via hydrophobic interaction with Aβ, and (3) enhancing Aβ clearance with Aβ complexes to promote cellular uptake, degradation, and efflux of Aβ through the BBB for clearance [40]. The gene discussed is APP; the disease is Alzheimer disease.