Complexity of MEF2D genomes in B-ALL. Genomic landscape of MEF2D-rearranged B-ALL. (A-B) Circos plots showing high SV burden in the 2 MEFDr cases with chromothripsis. The circos plot shows 4 concentric panels, and the outermost ring shows the chromosome ideogram. The second ring shows the intermutation distance for all SNVs color-coded by the pyrimidine partner of the mutated base (C>A, blue; C>G, black; C>T, red; T>A, gray; T<C, green; and T>G, pink). The third ring shows small insertions (dark green) and deletions (dark red). The fourth ring shows copy number change gains (green) and losses (red). Intra- and interchromosomal SVs are shown by arcs describing translocations (black), inversions (blue), deletions (red), and duplications (green). Circo plot (C) and locus plot of 1q21 (D) showing the “quiet” global SV burden and complex causative local SV event in an MEF2D::BCL9 case. In the locus plot in panel D are shown SV events as arcs between 2 breakpoint loci, with the color denoting the type of SV (top); the absolute copy number (middle); and the 2 causative SVs (inversion and deletion) overlaying the transcript structure of BCL9 and MEF2D (bottom). DEL, deletion; DUP, duplication; INV, inversion.