Activity of CP is clearly important for retinal health, as patients with the autosomal recessive disease aceruloplasminemia (no ceruloplasmin) have degenerative changes in the peripheral or macular RPE (Dunaief et al., 2005; Wolkow et al., 2011), in addition to a Parkinson's-like neurodegeneration. Here, CP is linked to aceruloplasminemia.