Thus, several groups attempted to design therapeutic strategies targeting TREM2 or sTREM2 for AD, including increasing TREM2 or sTREM2 level, activating TREM2, etc. Recently, Lee et al. conducted a gain-of-function genetic approach to generate TREM2 transgenic mice expressing human TREM2 in microglia [120], in order to determine whether increased TREM2 expression had impact on the development of AD. This evidence concerns the gene TREM2 and Alzheimer disease.