Typical mutations were detected in these breast cancers with the expected frequencies and association to clinicopathological characteristics: for example, 17/49 (35%) cases were determined to harbor mutations in the oncogene PIK3CA and these occurred most frequently in luminal A (8/14), HER2-enriched (3/8), and normal-like (2/4) tumors [35,44]. The gene discussed is PIK3CA; the disease is breast cancer.