V_H gene usage and mutation distribution. (A) The number of B-CLL V_H sequences using genes of each V_H family are shown in the center donut and the number of sequences using particular V_H1, 3, and 4 genes are depicted peripherally. The V_H gene used by each sequence was assigned using DNAPLOT and IgBlast. (B) Overall distribution of mutations per sequence. The colored arcs encompass sequences with less than 2% mutation (blue), 2% to 5% mutation (green), or more than 5% mutation (red). (C) The distribution of mutations in sequences using the 3 most commonly used V_H families: V_H1 (left), V_H3 (middle), and V_H4 (right). The distributions are shown when all genes of the family (top), the most commonly used gene of the families (middle), and the other genes of that family (bottom) are considered.