DNMT1 and Alzheimer disease: Also, Bihaqi and Zawia (2012) showed a significant latent increase in AD biomarkers an a reduction in the protein and mRNA levels of DNA methylating enzymes Dnmt1 and Dnmt3a, and methyl CpG binding protein 2 (MeCP2) in differentiated SH-SY5Y cells treated with Pb (5–100 μM/48 h) and analyzed 6 days later (Bihaqi and Zawia, 2012).