In contrast to germline loss of other components of the ubiquitin machinery, including LUBAC, OTULIN, and c-IAP1/2, that result in embryonic lethality, A20 deficient mice survive to birth, but subsequently develop multi-systemic inflammation that includes dermatitis, hepatitis, nephritis, enteritis, and arthritis (Lee et al., 2000). The gene discussed is TNFAIP3; the disease is arthritic joint disease.