Summary of translocation breakpoints in multiple myeloma presentation samples. Genes with exon/intron boundaries and the location on the chromosome are marked and arrows indicate the direction of transcription. Breakpoints are indicated with vertical lines of color corresponding to the partner chromosome (eg, t(4;14) are shown as purple lines and t(6;14) as dark blue lines). Oncogenes overexpressed because of the translocation are shown in blue. On chromosome 14, the IGH constant regions are indicated by light blue boxes and the upstream switch regions as dark blue boxes. D_H segments and the IGHJ segment region are also annotated, as are V_H segments in which translocations were detected. Arcs on chromosome 14 indicate an unbalanced translocation in which 1 sample has 2 breakpoints, 1 from each derivative chromosome. On chromosomes 11 and 20, dashed vertical lines indicate breakpoints in which the partner breakpoint on chromosome 14 is located in the V or D segments. On chromosome 11, the open box indicates a 50-kb gap in the genomic sequence.