TREM2 and Alzheimer disease: While the prevalence of AD‐linked TREM2 variants is low, indeed the most common (R47H) affects 0.3–0.6% of the population (Guerreiro et al, 2013; Jonsson et al, 2013), the relative risk for individual carriers is high, twofold to 11‐fold above the general population (Finelli et al, 2015).