The results showed that TP53, PIK3CA, TTN, and MUC16 had a high mutation frequency in HER2+ BC, of which TP53 was 79% (Figure 5a) in Cluster A, 67% (Figure 5b) in Cluster B, and 33% (Figure 5c) in Cluster C. The biological functional alterations caused by mutations in Cluster A and Cluster B were mainly concentrated in the TP53 signaling pathway, while they were mainly concentrated in the RTK-RAS signaling pathway in Cluster C subtype (Figure 5d). The gene discussed is PIK3CA; the disease is breast cancer.