Chimeric transcripts produced from Igμ/BCL6-translocated B cells. Shown on the left is a diagram of the germ-line BCL6 locus in chromosome 3 (Chr. 3) and Ig locus in Chr. 14, their reciprocal Igμ/BCL6-translocated loci, and the generation of the chimeric Iμ-BCL6 and BCL6E1-Cμ transcripts from the fusion genes. The chimeric transcripts amplified from tonsillar and/or splenic B cells are shown on the right. For Iμ-BCL6 transcripts, the major product of the chimeric transcripts is Igμ-BCL6E2, whereas Igμ-BCL6E3 is the minor product. The arrows present the Igμ/BCL6 recombination junctions isolated from human CD38⁺ B cells shown in Figure 4. MMC indicates major mutation cluster; MTC, major translocation cluster.