Amplification of MYC (n=47, χ2P<0.0001), of CCNE1 and CCND3 (both n=7, χ2P=0.0003), of PIK3CA (n=9, χ2P<0.0001) and, as expected, mutations in TP53 (refs 12, 13, 14) (n=105, χ2P<0.0001) were predominant in basal subtype cancers, while mutations in GATA3(refs 8, 15) (n=25, χ2P=0.0006), and PIK3CA (n=74, χ2P<0.0001) and amplification of CCND1 (n=39, χ2P<0.0001) were largely restricted to luminal breast cancer, with the latter strongly related to luminal B cancers16, 17 (33/39 cases, χ2P<0.0001). The gene discussed is PIK3CA; the disease is breast cancer.