Figure 3: Repair of CRISPR-Cas9-induced DSBs in the subtelomeric region.

(a) Schematic diagram showing the strategy used to induce DSBs in the subtelomeric region (0.5 and 1 kb from the first TTAGGG sequence in Xp/Yp). (b) Western blot analysis of Cas9 expression. Non-transfected cells served as a transfection control (Ctl) and plasmid with scrambled sgRNA (Scr) was used as a control for induction of DSBs. (c) Representative images of DSB repair foci in the subtelomere region. Scale bar, 10 μm. (d) Quantification of c. All values are the average ±s.d. of three independent experiments (n=200). ^**P<0.01. The Student’s t-test was used to determine the statistical significance. (e) T7 endonuclease I (T7E1) susceptibility was used to screen and identify mutations and deletions introduced during DSBR. Cells exposed to scrambled sgRNA (Scr) were used as a control. The location of PCR primer hybridization, ∼1 kb apart, is shown. (f) A summary of the results from sequencing the PCR products.