The frequency of pathogenic and likely pathogenic (P/LP) variants in clinically actionable genes (BRCA1, BRCA2, PTEN, TP53, CHEK2, CDH1, ATM, PALB2, NBN, and NF1) was compared between women with a primary breast cancer (PBC) and SBC who underwent multigene panel testing at a single diagnostic testing laboratory. The gene discussed is ATM; the disease is breast carcinoma.