NFKB1 and MALT lymphoma: TNFAIP3 is the most frequently mutated gene in H. pylori negative gastric MALT lymphoma.TNFAIP3, a negative regulator of NF-κB, was the most frequently affected gene, with mutations detected in 23% (8/35) of cases, including one case carrying two mutations (both frameshift deletions) (Figure 1, Figure 2 and Figure 3).