YY1 and pancreatic insulinoma: Thus, collectively, at the DNA level, 22 of 26 insulinomas (85%) contain recurrent SNVs/MNVs/indels (YY1, H3F3A, KDM6A, MEN1, ATR) and/or recurrent CNVs (MEN1, EZH2) in genes encoding epigenetic modifiers (Fig. 1c), four of which are members of two key epigenetic modifying complexes, the polycomb group (EZH2, YY1) and the trithorax group (MEN1, KDM6A).