See Hsiao et al., August 2025, for a joint consensus recommendation for HRD testing - homologous recombination deficiency.
It's open access at J Molec Diagnostics and runs 20 pages.
https://www.jmdjournal.org/action/showPdf?pii=S1525-1578%2825%2900136-9
The authors' abstract reads:
Homologous recombination deficiency (HRD) is a genomic feature present in some malignant neoplasms and is attributed to the failure of the homologous recombination repair pathway. Tumors with an HRDpositive status may have a distinct prognosis and/or response to therapies, including poly (ADP-ribose) polymerase inhibitors.
The Association for Molecular Pathology assembled an expert panel to examine current practice and perform a scoping review of the medical literature pertaining to the molecular detection of HRD in the clinical setting. The expert panel examined the following topics: components of existing and proposed HRD and genomic instability biomarkers (including mutational signatures, loss of heterozygosity, mutations in homologous recombination repair associated genes, and epigenetic silencing of RAD51C, BRCA1, or BRCA2); technical considerations for identifying genomic scars from tumor and germline next-generation sequencing results; guidelines on interpretation and caveats when reporting assessments of genomic instability and HRD scores; and the clinical significance of HRD.
The panel formulated a set of expert consensus opinion recommendations regarding HRD assay design and validation to guide laboratories in developing HRD tests to ensure high-quality and reproducible results.
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From the introduction,
[T]here is no universal definition of what constitutes HRD, which makes it difficult for laboratories to offer such testing. In the United States, there is currently one FDA-approved agent whose labeling defines HRD, describing it as a deleterious or suspected deleterious mutation in BRCA and/or genomic instability (olaparib package insert, per manufacturer instructions); however, genomic instability also has no universally agreed upon definition. At the time of this publication, one commercially available test is approved by the FDA to assess HRD (Myriad Genetics MyChoice CDx, Salt Lake City, UT). This assay uses a composite of tumor BRCA status and LOH, TAI, and LST to assess genomic instability.
