However, HRD assays are not clinically used or validated for other tumour types, and these tests are mostly focused on the detection of mutations in HRR genes—thereby missing some other causes of HRD such as BRCA1 promoter hypermethylation, which is present in 11% of ovarian cancer and 13–25% of breast cancers [271]. Here, BRCA1 is linked to breast carcinoma.