The authors identified a protective genetic allele associated with lower PU.1 (SPI1) expression in myeloid cells by conducting a genome-wide scan of Alzheimer's disease (AD). PU.1 binds the promoters of AD-associated genes (e.g., CD33, MS4A4A & MS4A6A, TYROBP) and modulates their expression, suggesting it may reduce AD risk by regulating myeloid cell gene expression.