Structural variations involving MYC in BL. Translocations between the MYC locus (chromosome 8) and the IGH (chromosome 14), IGK (chromosome 2), or IGL (chromosome 22) loci in tumors with IG-MYC breakpoints detected from WGS (N = 212). The subset of IGH-MYC breakpoints with high-confidence breakpoint positions identified are colored on the basis of their category, as determined by location within IGH (red = CSR, or blue = SHM). Bar charts on the lower left display the frequency of IG-MYC breakpoints (left) and IGH breakpoint category (right). The lower part of A and B linearly depicts IGH-MYC rearrangements colored by breakpoint category. (A) Adult (N = 80) and pediatric (N = 132) samples are shown separately. (B) EBV-negative (N = 103) and EBV-positive (N = 109) samples are shown separately. The inferred IGH breakpoint category frequencies stratified by age (C) and EBV status (D) were subjected to a Fisher exact test (∗∗P < .01). (E) AICDA expression in adult and pediatric BL tumors separated by EBV status (Wilcoxon rank sum test; ∗∗∗P < .001). AICDA, activation-induced cytidine deaminase; CSR, class-switch recombination; IGH, immunoglobulin heavy chain; IGK, immunoglobulin light chain kappa; IGL, immunoglobulin light chain lambda; SHM, somatic hypermutation.