Figure 1From: DNMT1 genetic polymorphisms affect breast cancer risk in the central European Caucasian populationThe DNA methyltransferases (DNMTs) are divided into two groups on the basis of their functional activities: de novo (a) and maintenance of DNA methylation (b). De novo DNMTs (DNMT3A and DNMT3B) can create m5CpG dinucleotides from unmethylated DNA, while the maintenance of methyltransferase DNMT1 attaches methyl groups to hemimethylated DNA during replication.Back to article page