The DNA methylation analysis of purified CD14+ monocytes from 15 T1D–discordant monozygotic twin pairs has evidenced hypermethylation in 54 genes and hypomethylation in 74 genes, some of which (TNF, TRAF6, CD6 and GAD2, HLADQB1, NFKB1A, respectively) are associated with T1D development (121). The gene discussed is GAD2; the disease is type 1 diabetes mellitus.