A20 inactivation in ocular adnexal MALT lymphoma

Recent studies showed A20 inactivation by deletion, mutation and promoter methylation in ocular adnexal mucosa-associated lymphoid tissue lymphoma. However, the incidences of A20 abnormalities and their clinical impact remain for the most part unknown. It is also unknown whether ABIN-1 and ABIN-2, the components of the A20 NF-κB inhibitor complex, are inactivated by genetic changes in ocular adnexal mucosa-associated lymphoid tissue lymphoma. A total of 105 cases were investigated for A20 mutation/deletion, ABIN-1/2 mutation, MALT1 and IGH involved translocation. Somatic mutation was seen frequently in A20 (28.6%) but rarely in ABIN-1 (1%) and ABIN-2 (1%). A20 mutations were significantly associated with A20 heterozygous deletion, and both were mutually exclusive from the MALT1 or IGH involved translocations. A20 mutation/deletion was also significantly associated with increased expression of the NF-κB target genes CCR2, TLR6 and BCL2. The cases with A20 mutation/deletion required significantly higher radiation dosages to achieve complete remission than those without these abnormalities.