ATM and hyperinsulinemic hypoglycemia, familial, 4: Although BRCA1 and BRCA2 mutant tumours are the best-known associations of HR deficiency and intrinsically sensitive to PARP inhibitors, there are a wide range of other non-BRCA DNA repair genes associated with HR deficiency, including but not limited to ARID1A, ATM, PALB2, CHEK2 and FANCA [23].