Neurons infected with the APOER2 Δex4-5, +ex6B, Δex15 variant that was found unique to AD brain exhibited a decreased in the number of synapsin (p = 0.0018) and PSD95 (p = 0.0166) puncta compared with control-specific APOER2 Δex4-5, +ex6B, Δex18 culminating to a 54% decrease in the total number of synapses (p < 0.0001, Fig 7A and 7D). Here, DLG4 is linked to Alzheimer disease.