TREM2 and Norrie disease: Few studies investigated the role of TREM-1 in the CNS (Aldrich and Kielian, 2011), whereas most brain-related studies focused on TREM-2 (Lue et al., 2015; Ulrich et al., 2017; Yeh et al., 2017) and its mutations that could lead to a chronic ND, named Nasu–Hakola disease (Nguyen et al., 2002).