TREM2 and Nasu-Hakola disease: TREM2 variants have been reported in a diverse array of neurodegenerative disorders, including NHD, FTD, AD, PD, semantic variant of primary progressive aphasia (svPPA), and ALS (Bonham et al., 2017; Dardiotis et al., 2017; Kleinberger et al., 2014).