Boehm et al.27 determine the homologous recombination deficiency (HRD) status of patients by investigating COSMIC signatures as direct evidence of HRD, in addition to sequencing for known predisposing variants (e.g. in BRCA1 and BRCA2 genes). The gene discussed is BRCA1; the disease is hypoparathyroidism-retardation-dysmorphism syndrome.