In blood from AD patients, B3GALT4 (beta-1,3-galactosyltransferase 4), a gene associated with AD onset and progression, and PTGR3 (prostaglandin reductase 3), associated with AD risk, are hypomethylated and correlate with memory performance and cerebrospinal fluid (CSF) levels of Aβ and tau [58]. The gene discussed is PTGR3; the disease is Alzheimer disease.