In this regard, deprivation of folate and vitamins B6 and B12 led to hypomethylation and overexpression of the β-secretase 1 (BACE1) and presenilin 1 (PSEN1) genes in cell cultures, transgenic AD animal models, and post-mortem brains of AD patients [70,71,72,73,74]. The gene discussed is PSEN1; the disease is Alzheimer disease.