The genetic testing described was performed as part of standard diagnostic testing within MCGM.5 A series of 77 women with ovarian cancer (9 borderline and 1 granulosa cell tumour in addition to EOCs) were screened for MMRD and HRD germline PVs by sequencing, multiple ligation-dependent probe amplification and a prescreen for MMR immunohistochemistry (IHC) as previously described.5 We also assessed the proportion of known carriers that developed EOC at age <30 and 30–34 years from our extensive dataset of >4000 female BRCA1/2 carriers and 910 MMRD heterozygotes. Here, BRCA1 is linked to ovarian cancer.