Alzheimer's disease (AD) is a neurodegenerative condition characterized by microglia-mediated neuroinflammation. Deep (>1,000×) panel sequencing of 311 brain samples revealed enrichment of somatic single-nucleotide variants (sSNVs) in cancer driver genes in AD brains, especially in genes associated with clonal hematopoiesis (CH). These sSNVs were associated with clonal expansion and carried by both microglia-like brain macrophages (MLBMs) in multiple brain regions as well as paired blood, suggesting a likely hematopoietic origin. Single-nucleus RNA sequencing data from 62 additional AD and control brains revealed increased somatic copy number variants (sCNVs) associated with CH in AD MLBMs, whereas single-cell multi-omic analyses demonstrated that sSNV- and sCNV-carrying MLBMs exhibited inflammatory and proliferative transcriptional signatures characteristic of disease-associated microglia. These signatures were recapitulated in induced pluripotent stem cell-derived microglia-like cells with TET2, ASXL1, and DNMT3A variants. These findings suggest that clonal somatic driver variants in MLBMs are enriched in AD, potentially promoting neuroinflammation and neurodegeneration.
Huang et al. (Wed,) studied this question.