TREM2 and Alzheimer disease: Although the presence of any of these rare TREM2 variants in our limited AD cohort is highly improbable, these studies together with our present data strongly suggest that microglial pathology, with the consequent deficient immunoprotection in relatively large areas of the hippocampus, such as the dentate gyrus and CA3, might, indeed, contribute to the progression of AD pathology and cognitive impairment.