Fig. 5. Accessible chromatin and mtDNA mutational dynamics during transformation to Richter’s syndrome.

(A) Circulating white blood cell count (CLL9). Analyzed samples are peripheral blood during CLL phase (CLL; black) and peripheral blood, bone marrow and lymph node at time of Richter’s transformation (Richter; magenta).

(B) UMAP plot of CLL, Richter’s and immune cells based on chromatin profiles (n=30,395) with identification of CD4⁺ T cells, CD8⁺ T cells, physiologic B cells, CLL cells from peripheral blood (PB), Richter’s cells from lymph node (LN), peripheral blood and bone marrow (BM).

(C) Heteroplasmy of mtDNA mutations and inferred copy number changes from scATAC-seq data of cells in clusters identified in (B). Only cells with at least one detectable mtDNA mutation are shown.

(D) Heteroplasmy of 3412G>A and 9553G>A in Richter’s cells. Coloring of dots indicates sequencing coverage (20-350x). Inset table shows number of cells with both, either one or none of the mutations detectable.

(E) Distribution of heteroplasmy of 3412G>A (blue) or 9553G>A (red) in Richter’s cells.

(F) Differential chromatin accessibility of transcription factor motifs between CLL (CLL PB1, CLL PB2) and Richter’s cells (Richter LN1, Richter LN2, Richter PB, Richter BM). Precision limit for adjusted p-value 2.6e-297.

(G) Chromatin accessibility of POU2F2 motif across clusters.

(H) Differential gene expression of scRNA-seq profiles of CLL cells from peripheral blood (CLL PB; black) and Richter’s cells from peripheral blood (Richter PB; magenta) or bone marrow (Richter BM; magenta).