Figure 3. Micro- and episomal insertions are recurrently found in monoallelic TAL1⁺ ‘unresolved cases’.

(a) Nucleotide sequences of episomal/microinsertions. All insertions were specifically and exclusively located at the indicated genomic position, and are pictured in red. Nucleotide deletions are indicated by a red dash. No SNPs are referenced at this position (Supplementary Fig. 8); (b) Relative TAL1 expression in T-ALL patients (n=111) according to biallelic (BI), or monoallelic (MONO) expression; patients with micro/episomal insertions are indicated in red; SIL-TAL cases are shown separately; informative cases: the presence of SNPs in TAL1 3’UTR allows to determine if the expression is mono- or biallelic. NI: non-informative cases (absence of SNPs in TAL1 3′ UTR does not allow to determine if the expression is mono- or biallelic). The average physiological TAL1 levels in thymus is shown as reference (Thymus); Horizontal bars indicate median expression levels; **indicates significant difference between BI and MONO expression (Mann–Whitney U-test, P<0,01); note that a number of biallelic patients are reaching/below physiological thymus levels, and might result from the presence of residual TAL1-expressing erythroblasts among tumoral cells43; TAL1 expression was analyzed by Taqman assay and is normalized to ABL (see Methods).