Indeed, at least one allele of TNFAIP3 encoding A20 is frequently targeted by mutations, deletions, or epigenetic silencing which result in a partial or complete loss of its negative regulatory function in several lymphoid malignancies, such as HL (approximately 45% of cases), PMBL (30%), ABC DLBCL (25%), and MALT lymphoma (20%) [160,161,162,163]. This evidence concerns the gene TNFAIP3 and MALT lymphoma.