Following microglial activation, MS4A4A shows increased expression.41 Similarly, MS4A4A is upregulated in activated dendritic cells (DCs) and M1 macrophages, while not detected in immature DCs and M2 macrophages.42 Here, MS4A4A showed significantly altered expression in the PFC region of AD brains (P = 1.08E−24), yet displayed an expression alteration of suggestive evidence in the hippocampal region (P = 3.87E−03). The gene discussed is MS4A4A; the disease is Alzheimer disease.