Exposure to 50 μM of H2O2 induced a significant increase of RAD51 foci per cell either in healthy (ctr vs. 50 μM H2O2: 0.5 ± 0.2 vs. 41.3 ± 4.2, p < 0.01) or in SSc fibroblasts (ctr vs. 50 μM H2O2: 17.2 ± 4.2 vs. 66.3 ± 5.3, p < 0.01), although the number of RAD51 foci was significantly higher in the SSc (p < 0.01). The gene discussed is RAD51; the disease is systemic sclerosis.