Different next-generation sequencing (NGS) studies [78–83] have demonstrated that the most frequently mutated genes in breast cancer are PIK3CA (31–41%), TP53 (30–36%), KTMC2 (7–11%), GATA3 (10–11%), MAP3K1 (7–10%), and CDH1 (10–11%). The gene discussed is PIK3CA; the disease is breast carcinoma.