In addition, gastric tumor cells exhibited evident DNA damage and DNA repair defect, supported by downregulation of well-known genes involved in DNA damage and repair response, including RAD51, BRAC1, BRCA2 and BARD1 (Fig. 4E; Supplementary Figs. S3D-F; S4A) [50, 51]. This evidence concerns the gene RAD51 and gastric neoplasm.