IGKV amino acid sequences of 5 cases with CLL cells expressing M-IGHV3-21 with HCDR3 motif1, U-IGLV3-21, and in-frame IGKV-J-KDE rearrangements. Capital letters indicate amino acid changes resulting from R mutations. Hyphens indicate homology at that position to the respective reference IGKV amino acid sequence. Listed on the left is the designation for each CLL sample.