We chose these genes as their methylation levels previously have been found to associate with age in blood (all four genes, Supplementary Data 8), they showed functional effects in β-cells (FHL2 and ZNF518B, Fig. 4) or have been associated with T2D risk (KLF14 (refs 28, 29)). The gene discussed is ZNF518B; the disease is type 2 diabetes mellitus.