The MALT1 Breakapart probe consists of two green clones (132kb and 306kb) and two red clones (171kb and 228kb), which are positioned on each side of the MALT1 gene.
Extranodal marginal zone B-cell lymphoma (MZBCL) of the Mucosa-Associated Lymphoid Tissue (MALT) type is characterised by two main translocations involving MALT1; t(11;18)(q21;q21.32) and t(14;18)(q32;q21.32)1. Other MALT1 associated translocations are rare1.
However, there are no MALT1 translocations in nodal or splenic lymphomas1. The t(11;18) BIRC3 (Baculoviral IAP repeat containing 3 protein2,3)/MALT1 translocation is present in 18-33% of cases of MALT lymphoma2 and the resulting fusion protein induces NF-κB (nuclear factor kappa-light-chain-enhancer of activated B-cells), resulting in transcriptional activation3. 18% of MALT lymphomas harbour the t(14;18) MALT1/IGH translocation4.
The genetic abnormalities in MALT lymphomas reflect their site of origin. The t(14;18) translocation was most frequently found in MALT1 lymphomas of the parotid gland, liver, skin, and ocular adnexa – sites rare for the t(11;18). However, the pulmonary and gastrointestinal MALT lymphomas show high frequencies of t(11;18) and absence of the t(14;18)1,4.