The hippocampus and frontal cortices of AD brains were shown to have considerably lower levels of CX3 C chemokine ligand 1 (CX3CL1) and CX3CR1 compared to controls [105], suggesting that signaling through CX3CL1/CX3CR1 is impaired in AD. The gene discussed is CX3CL1; the disease is Alzheimer disease.