These changes in human CX3CR1 decrease CX3CL1 affinity (McDermott et al., 2001) and have been associated with multiple neurodegenerative disorders such as age-related macular degeneration (Chan et al., 2005; Schaumberg et al., 2014), Alzheimer’s disease (Lopez-Lopez et al., 2017), and multiple sclerosis (Arli et al., 2013; Cardona et al., 2018). Here, CX3CL1 is linked to age-related macular degeneration.