Variant t(2;18) and t(18;22) chromosome translocations observed in B-cell chronic lymphocytic leukemias and in follicular lymphomas have been reported to consistently involve the 5' region of the BCL-2 gene on chromosome 18 and various regions on the lg light chain loci. We show here that a variant t(2;18)(p11;q21) translocation observed in a case of follicular lymphoma leads to the juxtaposition of a J kappa segment to a chromosome 18 transcriptional unit located 10 kpb upstream of the BCL-2 locus. The cDNA of this new evolutionarily conserved gene, termed FVT-1 for follicular-variant-translocation gene, codes for a putatively secreted protein of 36 Kd that is not homologous with any described protein. The FVT-1 gene is weakly expressed in all the analyzed normal hematopoietic tissues but a very high rate of transcription is observed in some T-cell malignancies and in phytohemagglutinin-stimulated lymphocytes. The proximity of FVT-1 to the BCL-2 locus suggests that in the t(14;18) currently observed in follicular lymphomas, both genes would participate in the tumoral process.