Sequence logos of selected major subsets in CLL. (A) Subset 6 comprises 68 unmutated IGHV1-69/IGHD3-16/IGHJ3 rearrangements, characterized by pronounced overall similarity. In fact, except for 4 VH CDR3 positions (encircled by brackets), which were characterized by variability, all other 17 positions were extremely, if not entirely, conserved. (B) Subset 2 is the largest high-level subset in the present study. Rearrangements belonging to this subset can be simply identified by a 9-aa long VH CDR3 with an acidic residue (aspartic acid D) at position 107 (encircled by brackets). The height of symbols within the stack indicates the relative frequency of each amino acid at that position. Amino acid position is according to the IMGT numbering for the V domain.²⁷