We queried the normal tissue from 40 samples with paired tumor, looking for significantly mutated genes from our first The Cancer Genome Atlas project (TCGA) breast cancer manuscript.19 Thirty-one of the 40 paired tumors had mutations (n=53) representing 17 significantly mutated genes, including 18 PIK3CA mutations and 11 TP53 mutations. The gene discussed is PIK3CA; the disease is breast carcinoma.