Mean genetic distances within the core-coding region between early and late clonal sets for progressors and nonprogressors. Distance was calculated by the mean Kimura 2-parameter pairwise distances for each patient. At baseline, there were no statistically significant differences in diversity between progressors and nonprogressors. Over time, 5 progressors and 1 nonprogressor showed a decrease in genetic distance within early and late sets of clones. However, mean between-group genetic distances for early and late clonal sets were 0.04 (SE- 0.01) and 0.02 (SE- 0.003) for progressors versus nonprogressors, respectively (P = .02, data not shown); 80% of the progressors had greater overall genetic distance than their matched controls.