Clonal branching through loss of heterozygosity by mitotic recombination. (A) Putative evolutionary tree generated from the classification of all sorted BM CD34⁺ clones (n = 106; pooling all subpopulations) for UPN #638 accounting for the heterozygosity status at each locus, showing multiple branching with LOH of the CBL and SF3B1 mutation (italicized: heterozygous, bold & underlined: homozygous). (B) Corresponding Sanger sequences at the SF3B1 locus of CD34⁺ clones from UPN #638 with wild-type, heterozygous, and homozygous SF3B1 according to the TaqMan allelic discrimination assay showing the mutation region (top panel) and the informative SNP rs77741206 located 46 bp in the 3′ intronic region. Sequences from total CD14⁺ cells of UPN #638 and from the UT7 cell line as control. (C) Putative evolutionary trees of sorted BM CD34⁺ populations from UPN #507. White: no mutation, yellow: 1 mutation, orange: 2 mutations, red: 3 mutations, purple: 4 mutations. Only mutated genes are indicated in each subclone (italicized: heterozygous, bold and underlined: homozygous).