PDX1 and type 2 diabetes mellitus: For instance, pancreatic duodenal homeobox 1 (PDX-1) mutations can cause a monogenic form of maturity-onset diabetes of the young, in which the CpG sites in the distal promoter and enhancer regions exhibited significantly increased DNA methylation in the pancreatic islets of type 2 diabetes (T2D) patients (Yang et al., 2012).