MRE11 and Huntington disease: The MRE11 foci kinetics obtained from the HD, TSC, and XPD cells are also shown in Figure 5B. The data obtained from the HD, TSC, and XPD fibroblasts tested showed significantly higher numbers of MRE11 at 1 h and 4 h post-irradiation (p < 0.05), and a higher number of MRE11 foci at 24 h post-irradiation (p < 0.1), compared to USH1 data, suggesting a different involvement of MRE11 nuclease in the response of USH1 cells to IR than in the other syndromes tested (Figure 4B).