A20, also known as tumour necrosis factor‐α‐induced protein 3 (TNFAIP3), is an ubiquitin‐modifying enzyme that has amino‐terminal deubiquitinating activity mediated by its ovarian tumour domain, and has a carboxy‐terminal zinc finger domain that supports E3 ubiquitin ligase activity. This evidence concerns the gene TNFAIP3 and ovarian neoplasm.