KMT2D and MALT lymphoma: In OAMZL, the most commonly reported epigenetic mutated gene is KMT2D with frequencies varying from 14% to 22% [160,161,168], and in Helicobacter pylori-negative gastric MALT lymphoma, KMT2D (17%) and CREBBP (14%) are the two most epigenetic regulator gene mutations [189].