Given the complexity of HRD biomarkers, key assay features include the selection of HRR genes (BRCA1, BRCA2, PALB2, RAD51C, RAD51D), definitions of genomic scars (LOH, TAI, LST), mutational signatures analyzed, use of comparator samples, and tumor-specific HRD score calculations. The gene discussed is RAD51C; the disease is neoplasm.