CDRs of B-CLL sequences contain more replacement mutations. (A) Number of replacement mutations at each position in the V_H genes of B-CLL. (B) Number of silent mutations observed at each position in the V_H of B-CLL. (C) A “moving window” R/S ratio for each position was calculated by considering the cumulative R/S ratio of the centered position and the 5 (dotted line), 6 (dashed line), or 7 (solid line) positions on either side. CDR and FR are as defined by Kabat et al.²⁴