PIK3CA and breast cancer: PIK3CA (34%), TP53 (34%), TTN (17%), CDH1 (13%), GATA3 (13%), MUC16 (10%), MAP3K1 (9%), KMT2C (9%), HMCN1 (6%) and RYR2 (6%) were the top five genes with the highest mutation frequencies in BC (Figure 4F).