Mono- and bi-allelic inactivation of A20 in MZL. (A) Distribution and features of A20 mutations in MZL. Schematic representation of the human A20 protein with its functional domains (OTU indicates ovarian tumor domain, mediating the deubiquitinating activity of A20; ZF, zinc-finger domain, exerting the ubiquitin ligase activity of A20); the cleavage site of A20 by the MALT1 protease¹⁸  is also indicated. The approximate location of A20 mutations is indicated below the map with triangles, and the types of mutations are described in detail in the table. *In these cases, the somatic origin of the mutation was confirmed by analysis of matched normal DNA. (B) Frequencies of A20 mutations and genetic loss in MZL subtypes. (C) Allelic distribution of A20 inactivation by mutations and deletions and known recurrent cytogenetic aberrations for all MZL cases analyzed. Each column represents 1 case, and the sites of the EMZL are indicated.