Among these DDR DEGs, there were 7 DDR genes (POLQ, BRIP1, FANCA, XRCC2, EXO1, and EME1) identified in nine or more cancer types and 13 DDR genes (BLM, BRCA2, RAD51, SHFM1, BRCA1, UBE2T, SLX1A, FANCB, FANCD2, FEN1, ERCC3, GEN1, and PRKDC) were found in four to nine kinds of cancers. The gene discussed is RAD51; the disease is cancer.