Among them, RECOL, CUL4A, PARP4, HES1, FANCE, OGG1, XRCC2, UNG, PPP4R2, POLN, PER3, HUS1, DDB2, DCLRE1C, and BLM were found to be dramatically increased in AD brain tissue samples, while a significant decrease in the expression levels of other 36 genes including UBE2N, CCNH, RAD51C, XRCC5 and et al. The gene discussed is XRCC5; the disease is Alzheimer disease.