CX3CL1 and early-onset autosomal dominant Alzheimer disease: For example, neuronal ligand CX3CL1 (fractalkine) signals to microglia through CX3CR1 altering immune signaling, synaptic plasticity (Sheridan et al. 2014), as well as amyloid β-complement processing in Alzheimer’s disease models (Lian et al. 2015).