TREM2 and Alzheimer disease: For example, the respective influence of APOEε4, with and without Trem2*R47H expression, in regional changes in brain glycolytic metabolism (Murray et al., 2014; Figure 3, Supplementary Figure 6), tissue perfusion (Thambisetty et al., 2010; Roher et al., 2012; Figure 4, Supplementary Figure 7) observed in human AD remain under further study.