t(3;14)(P14.1;Q32) Involving IGH and FOXP1 Is a Recurrent Chromosomal Aberration in MALT Lymphoma.

Translocations t(11;18)(q21;q21), t(14;18)(q32;q21), and t(1;14)(p22;q32) are known to occur in MALT lymphoma. In a patient with MALT lymphoma of the thyroid a novel t(3;14)(p14.1;q32) was observed by cytogenetic analysis. Subsequent fluorescence in situ hybridization studies showed that the immunoglobulin heavy chain locus (IGH) was rearranged on chromosome 14. Long-distance inverse polymerase chain reaction identified FOXP1 as the partner gene on chromosome 3. Two FISH-assays were established to screen 90 MALT lymphomas, 8 splenic and 6 nodal marginal zone lymphomas for this aberration. Overall, 8 MALT lymphomas (9%) harbored t(3;14)(p14.1;q32); the aberration was detected in MALT lymphomas of the ocular adnexa (4 of 20), thyroid (2 of 5), and skin (2 of 20), but not in the stomach (n=20), salivary gland (n=20), and lung (n=5). Splenic and nodal marginal zone lymphomas were t(3;14)(p14.1;q32) negative. Further 38 MALT lymphomas with known t(11;18)(q21;q21), t(14;18)(q32;q21), or t(1;14)(p22;q32) did not reveal a t(3;14)(p14.1;q32). Most t(3;14)+ MALT lymphomas (7 of 8) harbored additional genetic abnormalities, such as +3. Real-time quantitative RT-PCR showed up-regulation of FOXP1 in cases with t(3;14)(p14.1;q32) or trisomy 3. This study identifies FOXP1 as a new translocation partner of IGH in MALT lymphomas.