Amino acid sequence logos of IGHV3-21 and IGHV3-23 rearrangements with less than 100% GI. Seventy-eight IGHV3-21 and 48 IGHV3-23 rearrangements are depicted. The letters above the line represent the amino acid changes, whereas the letters shown upside-down below the line represent the corresponding germ line amino acids of the IGHV gene. The size of the amino acid symbol represents the relative frequency of that amino acid at that position relative to all other mutations at that position in the certain IGHV group of sequences. Blank spaces represent amino acids that are unchanged in comparison to the germ line sequence. Amino acids are colored based on their similarity in terms of their physicochemical properties, as described previously. For example, in the IGHV3-21 group, the substitution of S for N at VH CDR1 codon 38 occurred in 15/78 (19.2%) cases, whereas in the IGHV3-23 group, the amino acid changes S-to-N at VH CDR1 codon 36 and V-to-I at VH FR3 codon 101 were detected in 12/48 (25%) cases each, respectively. Additional detailed information is provided in supplemental Table 12A and B.