The levels of synapse‐related proteins, including PSD95, SYN and VAMP1, but not SNAP25, were reduced in the brains of AD mice underwent splenectomy compared to those in sham mice (t = 2.28, p = 0.039 for PSD95; t = 2.23, p = 0.046 for SYN; U = 16, p = 0.032 for VAMP1; t = 1.21, p = 0.25 for SNAP25; Figure 5f). The gene discussed is DLG4; the disease is Alzheimer disease.