Unsupervised analysis of paired diagnostic and relapse samples. (A) Samples (70; 35 patients at diagnosis and relapse) were clustered by hierarchic clustering using the Pearson correlation coefficient as the similarity measure. The diagnostic and relapse samples from multiple patients clustered closely together. D indicates sample from initial diagnosis; R, sample from relapse. (B) The Pearson correlation coefficient (CC) of the paired sample for each patient (32 pre-B) is represented as a gray circle; the higher the CC, the more similar the paired samples. Patients have been arranged from left to right according to the length of time to relapse. There is a clear trend toward decreasing CC as the time to relapse increases, as indicated by the regression line (P value of F test = .002).