Amino acid sequences of the HCDR3 in the IGHV3-21 cases. Alignment of the HCDR3 sequences belonging to 37 IGHV3-21 CLL cases was performed by converting all in-frame IGH rearrangements into aa sequences, selecting HCDR3 sequences only, and aligning them by means of the multiple sequence alignment software ClustalW.²¹  The length of HCDR3 was computed between codons 95 and 102, as described by Kabat. A black frame was drawn around the 18 sequences with the same length and similar aa composition. Missing aa's are indicated with dashes.