Since the ε4 allele of the apolipoprotein E (APOE) gene is the main genetic risk factor for late-onset AD [36], we further examined a possible link between global DNA methylation levels and the APOE gene variants APOE 2.3, APOE 3.3, APOE 3.4, and APOE 4.4; there was no correlation between 5mC levels and any of these APOE isoforms (Figure S2C,D). The gene discussed is APOE; the disease is Alzheimer disease.