Figure 2

Drug treatment in lymphoblastoid cells with a highly expanded mutation. A and B, Two untreated highly expanded and prone-to-expand cell lines (panel A: cell line with 80 CAG repeats; panel B: cell line with 74 CAG repeats) show an increased CAG repeat variation. The 6^th time yielded two peaks with a large level of mosaicism in both cell lines, in one (A) extended beyond 100 CAG repeats. Treatment with ethidium bromide (EB), ethylmethanesulphonate (EMS) and mitomycin C (Mit-C) progressively restricted the mosaicism and the expanded triplet variation in both cell lines. C, Mosaicism variation in treated and untreated cell lines. Untreated cell lines significantly increased their mosaicism degree observed at time 6 vs time 0 (*p = 0.019, see online/supplementary Table 3). Treated cell lines at time 6 significantly decreased their mosaicism degree vs time 0 (**p < 0.0001, see Additional file 1). Degree of mosaicism: median number of peaks observed at time 0 and 6 from two untreated and treated cell lines carrying large CAG repeat expansions. Statistical analysis performed by ANOVA. EB = ethidium bromide, EMS = ethylmethanesulphonate; Mit-C = mitomycin C.