Among the shared upregulated genes in normal breast tissues and breast tumors, the expression of five genes unique to young women aged ≤40 years with BC (i.e., COL1A2, COL5A2, COL5A1, NPY1R, and KIAA1644) significantly affected the OS and RFS of patients with several tumor subtypes (Figure 4a). The gene discussed is COL1A2; the disease is breast cancer.