Rearrangements in the MALT1 gene located on chromosome 18q21 and encoding MALT lymphoma translocation protein 1 are specific for MALT lymphomas; they include IGH/MALT1 translocation and API2/MALT1 fusion between the API2 (apoptosis inhibitor 2) and MALT1 genes20,21. This evidence concerns the gene MALT1 and MALT lymphoma.