APOE and Alzheimer disease: Using single-cell RNA sequencing (scRNA-seq) technology, Mathys et al. (2019) profiled ~80,000 single-nucleus cortical transcriptome samples from 48 patients with varying degrees of AD pathology and identified transcriptional profiles linked to AD pathogenesis, such as altered expression of genes involved in inflammation and Aβ clearance pathways, including APOE, TREM2, MHCII, and C1qb [281].