T(3;4)(p14.1;q32) involving IGH and FOXP1 is a novel recurrent chromosomal aberration in MALT lymphoma

The three chromosomal translocations t(11; 18)( q21; q21), t( 14; 18)(q32; q21), and t( 1; 14)( p22; q32) are associated with MALT lymphoma. In a case of MALT lymphoma of the thyroid, we observed t( 3; 14)( p14.1; q32) by cytogenetic analysis. 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. To determine the frequency of the t( 3; 14)( p14.1; q32), two fluorescence in situ hybridization assays were established to screen 91 MALT lymphomas, all of which were negative for the above-mentioned three translocations, and eight splenic and six nodal marginal zone lymphomas. Overall, nine MALT lymphomas (10%) harbored t( 3; 14)( p14.1; q32) comprising tumors of the thyroid ( three of six), ocular adnexa ( four of 20), and skin ( two of 20), whereas those of the stomach (n = 20), salivary gland ( n = 20), and lung ( n = 5) were negative as well as the splenic and nodal marginal zone lymphomas. Most t( 3; 14)( p14.1; q32) +MALT lymphomas harbored additional genetic abnormalities, such as trisomy 3. Further studies revealed that the three known translocations and t( 3; 14)( p14.1; q32) are mutually exclusive. Real-time quantitative reverse transcriptase polymerase chain reaction showed upregulation 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 a site-dependent subset of MALT lymphomas.