Fig. 7

The cancer cell fraction and timing of PIK3CA ^H1047R mutations in human breast cancer. a The cancer cell fraction of PIK3CA ^H1047R mutations in the TCGA breast cancer cohort. Each symbol represents a non-silent somatic mutation in an individual tumour. On the basis of the probability distributions of the cancer cell fraction, mutations were determined to be either clonal (red circles, upper bound of confidence interval ≥ 1) or subclonal (blue circles, upper band of confidence interval < 1). Error bars represent the 95% confidence interval. PIK3CA ^H1047R mutations are significantly more often clonal than subclonal (P < 0.001). b Timing of PIK3CA ^H1047R mutations in the TCGA genome-doubled breast cancer cohort. The proportion of PIK3CA ^H1047R mutations that likely occurred prior to genome doubling is depicted with a dotted line representing expected distribution based on background randomizations. The graph shows that the majority of PIK3CA ^H1047R mutations likely precede genome doubling, more than expected by chance (P < 0.0001). The proportion of pre-genome doubling is the proportion of PIK3CA ^H1047R mutations that occur pre-genome doubling. The distribution relates to the expected number of mutations occurring pre-genome doubling. This is based on taking the same number of mutations, and randomly sampling this 10,000 times. This gives an estimate of the likelihood that a random sample of mutations would show the same number of pre-doubled mutations