A positive family history of breast cancer in this patient prompted genetic testing, analyzing genes associated with hereditary breast and ovarian cancer (BRCA1, BRCA2, ATM, CDH1, CHEK2, PALB2, TP53, STK11, PTEN, NF1, RAD51C, and RAD51D) using next-generation sequencing (NGS). The gene discussed is CDH1; the disease is breast cancer.