Tumours enriched for APOBEC mutagenesis had better survival and were more likely to have mutations in both DNA damage repair and chromatin-modifying genes such as TP53, PIK3CA (primarily at E542 K and E545 K), ATR, BRCA2, MLL, MLL3 and ARID1A (figure 5). The gene discussed is PIK3CA; the disease is neoplasm.