The demyelination in neuromyelitis optica, a disorder related to multiple sclerosis, results from an autoimmune attack on aquaporin-4 in astrocytic foot processes (Lucchinetti et al. 2014); this may be relevant to other demyelinating conditions that could be triggered by mercury, since aquaporins are inhibited by mercury (Ximenes-da-Silva 2016). Here, AQP4 is linked to neuromyelitis optica.