For example, individuals with homologous recombination deficiency (HRD) due to BRCA mutations may benefit from PARP inhibitors (Mirza et al., 2016), while coexisting mismatch repair (MMR) deficiency (e.g., MSH2, PMS2) may make them eligible for immunotherapy (Le et al., 2017). The gene discussed is PMS2; the disease is hypoparathyroidism-retardation-dysmorphism syndrome.