Moreover, our analysis revealed biological processes associated with early brain impairment relevant to AD are marked by DNAm in the blood, and blood DNAm at several CpGs in the DMR on <i>HOXA5</i> gene are associated with pTau <sub>181</sub> in the CSF, as well as tau-pathology and DNAm in the brain, nominating DNAm at this locus as a promising candidate AD biomarker. The gene discussed is MAPT; the disease is Alzheimer disease.