TREM2 and Alzheimer disease: Trem2 mutations have been reported to be involved in the development of various neurodegenerative diseases, such as Nasu‐Hakola disease, Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS) (Benitez et al., 2013; Cady et al., 2014; Guerreiro et al., 2013; Jonsson et al., 2013; Paloneva et al., 2002).