TREM2 and atrial fibrillation: To explore whether other phagocytic activities were contributors to AF accumulation, we examined Fc-receptor mediated and Triggering Receptor Expressed on Myeloid cells 2 (TREM2)-mediated phagocytosis using Fcer1g−/− mice, which lack the common Fc-gamma chain required for functional expression of activating Fc-receptors (Takai et al., 1994), and Trem2−/− mice, which were reported to have microglia defective in the engulfment of apoptotic neurons, myelin debris, and synapses (Cantoni et al., 2015; Hsieh et al., 2009; Wang et al., 2015).