Non-carriers with aggregated amyloid and normal cognition showed lower levels of presynaptic proteins (NRX1 and NRX2), proteins involved intracellular trafficking (vacuolar protein sorting 10 [VPS10], domain-containing receptor SorCS1 [SORCS1]), and neuronal pentraxins [47], suggesting alterations in the presynaptic cell structure may be an early event in AD for subjects lacking the ε4 allele. Here, SORCS1 is linked to Alzheimer disease.