However, TREM2 R47H mutations appear to be relatively rare occurrences and may predispose only highly selective human populations to increased risk for age-related, pro-inflammatory neurodegenerative disorders such as AD (Gonzalez Murcia et al., 2013; Guerreiro et al., 2013; Hampel and Lista, 2013; Lattante et al., 2013; Bagyinszky et al., 2014). Here, TREM2 is linked to Alzheimer disease.