Elevated CSF BAFF levels are also observed in the acute relapse phase of NMO, which differs from that of MS (Quan et al., 2013; Vaknin‐Dembinsky, Brill, Orpaz, Abramsky, & Karussis, 2010; Wang et al., 2012). The gene discussed is TNFSF13B; the disease is neuromyelitis optica.