HTS of IGH in BL tumors reveals large families of closely related sequences. (A) Phylogenetic tree of all IGH sequences observed in a representative BL tumor sample. Unique IGH VDJ gene rearrangements are indicated by node color. The red arrow indicates the dominant unique sequence identified in the tumor. (B-G) Density plots of nucleotide edit distance (the number of nucleotide differences between a given unique sequence and the most frequent sequence in the tumor) for all sequences identified in all BL IGH samples (B), BL IGK/IGL samples (C), BL TRB samples (D), nonmalignant bone marrow and PBMC IGH control samples (E), bone marrow control IGK/IGL samples (F), and for CD8⁺ T-cell clones (G). (H) Clonal relatedness scores for each of the sample populations listed above (defined as the total number of distinct unique sequences with an edit distance <10 from the most frequent sequence, divided by the total number of unique sequences).