MUL1 and splenic marginal zone lymphoma: The genetic alterations of BIRC3 are also observed in 11% of 101 patients with splenic marginal zone lymphoma (SMZL), a small B-cell lymphoma.104 All somatic alterations, including 6 mutations and 5 deletions of the BIRC3 gene, are predicted to eliminate or truncate the E3 ubiquitin ligase activity of BIRC3, which blocks its inhibitory function on non-canonical NF-κB pathway activation, contributing to the development of SMZL.