We found 22 tumor-related gene mutations (APC, KRAS, SMAD4, ERBB4, TCF7L2, AMER1, TP53, GNAS, ARID2, RET, MTOR, NRAS, ACVR1B, GNAQ, ATM, PIK3CA, ERBB2, TRRAP, MAP2K4, MAP3K4, CNOT1 and EP300) from 12 HGCAs that harbored 2-7 of these mutations per case. The gene discussed is PIK3CA; the disease is neoplasm.