Graphical representation of IGHD and IGHJ gene associations in CLL and ALL. (A) Partial IGHD-IGHJ (D-J) rearrangements in CLL. (B) Partial IGHD-IGHJ (D-J) rearrangements in ALL. (C) Productive IGHV-IGHD-IGHJ (V-D-J) rearrangements in CLL. The graphs were prepared by using the Circos software package (http://mkweb.bcgsc.ca/circos). Strong biases are evident in the case of (a) the IGHD2-2 gene, which is very frequently recombined to the IGHJ6 gene in D-J; (b) the IGHD3-3 gene, which is recurrently recombined to the IGHJ6 gene in V-D-J; and (c) the increased usage of the IGHD7-27 and IGHJ6 genes in D-J in ALL.