An analog of cytidine in which a nitrogen atom is substituted for a carbon in the number 5 position of cytosine (q.v.). The analog is incorporated into newly synthesized DNA, and such DNA is undermethylated. Since a reduction in the number of methyl groups attached to genes is associated with an increase in their transcriptional activities, 5-azacytidine can switch on certain genes. For example, patients given the drug may start making fetal hemoglobin, which implies that their gamma genes have been switched on. See hemoglobin, hemoglobin genes.
Subjects: Genetics and Genomics.