SMARCA4 (BRG1) deficiency has been reported in several malignances [17–24], including small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), lung adenocarcinoma, medulloblastoma, Burkitt lymphoma, breast cancer, uterine sarcoma, and thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT). Here, SMARCA4 is linked to breast carcinoma.