This short paper is an update on some very recent observations on TREM2 neurobiology, on newly discovered roles for miRNA-34a-mediated signaling in human degenerative disease, including miRNA-34a-mediated effects on TREM2 expression, and how dysfunctional TREM2 signaling may contribute to amyloidogenesis in AD and in related progressive, inflammatory neurodegenerative diseases of the human CNS. The gene discussed is TREM2; the disease is Alzheimer disease.