SDC1 and triple-negative breast carcinoma: Moreover, SCUBE2, TMEM26, and SMOC2 were validated as subtype-specific coding genes in luminal A breast cancer, CDK12 and SDC1 in HER2 breast cancer and PSAT1 in triple negative breast cancer in TCGA and GEO datasets (Additional file 1: Fig. S4g–l and Fig. S5).