TREM2 and Alzheimer disease: Research on TREM2 missense mutations in European populations revealed that variants, such as L211P [24], H157Y [25], R136Q [26], T96K [26], D87N [27], T66M [26], R62H [28], R47H [27], and Q33X [29] (Fig. 2), have been found to be associated with AD.