In eutopic endometrial tissue of the control group, γ-H2AX expression was absent or faint in nuclei of stromal cells (Figure 1A); whereas most stromal cells in eutopic endometrium of patients with endometriosis showed moderate nuclear γ-H2AX expression (Figure 1B), and some stromal cells showed faint cytoplasmic γ-H2AX positivity. The gene discussed is H2AX; the disease is endometriosis.