In comparison, around 200 response genes were linked with PIK3CA mutations, and fewer than 100 response genes were identified for the non-driver control gene TTN. The observation that the majority of response genes displayed a single breakpoint (Fig 1D) suggests that patient-derived GATA3 mutations can be divided into two functionally distinct regions and that mutations in these regions are associated with differential gene expression in tumours. The gene discussed is PIK3CA; the disease is neoplasm.