Internal DNA deletion within the BCL-6 gene on untranslocated chromosome in non-Hodgkin's lymphoma with 3q27 abnormality.

Chromosomal translocations involving the band 3q27 are recognized as common specific cytogenetic abnormalities in B cell non-Hodgkin's lymphoma (NHL), and the BCL-6 gene, identified on 3q27 was shown to be disrupted by these translocations. Previously, we have reported biallelic BCL-6 rearrangements occurring in some patients with B cell NHL. In the present study, we describe a NHL patient with t(3;22)(q27;q11) translocation. In this patient, biallelic BCL-6 abnormalities were indicated by Southern blot analysis. Further studies revealed that one of the two independent abnormalities was a juxtaposition to the immunoglobulin (Ig) lambda gene associated with chromosomal translocation, whereas the other was an internal DNA deletion of 1.5 kb area on untranslocated chromosome 3. Deletion junctions were located within the first exon and the 5' region of the first intron. The result provides the evidence that, besides chromosomal translocation, submicroscopic local DNA recombination can cause structural alteration of the BCL-6 gene.