DNA damage repair deficiency, for example, through BRCA1/BRCA2, ATM or PALB2 loss, is seen in ∼15% of all pancreatic tumours (Pishvaian et al., 2018) and may represent a window of opportunity for radiotherapy in these patients due to increased radiosensitivity as a result of genomic instability (Karnak et al., 2014). The gene discussed is BRCA1; the disease is hyperinsulinemic hypoglycemia, familial, 4.