CD4 and Alzheimer disease: We confirmed this sex difference via droplet digital PCR of isolated CD4 T cells, finding that females with early-onset AD had heightened expression of the classical IFN response gene, MX1. In parallel, a meta-analysis of over 1.8 million CD4 T cells found that females have increased levels of a subpopulation of naïve T cells identified by expression of the same marker gene, MX1 (20).