Homologous recombination–deficient mutation cluster in tumor suppressor RAD51C identified by comprehensive analysis of cancer variants

Rohit Prakash, Yashpal Rawal, Meghan R. Sullivan, McKenzie K. Grundy, Hélène Bret, Michael J. Mihalevic, Hayley L. Rein, Jared M. Baird, Kristie Darrah, Fang Zhang, Raymond Wang, Tiffany A. Traina, Marc R. Radke, Scott H. Kaufmann, Elizabeth M. Swisher, Raphaël Guérois, Mauro Modesti, Patrick Sung, Maria Jasin, Kara A. Bernstein

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Mutations in homologous recombination (HR) genes, including BRCA1, BRCA2, and the RAD51 paralog RAD51C, predispose to tumorigenesis and sensitize cancers to DNA-damaging agents and poly(ADP ribose) polymerase inhibitors. However, ∼800 missense variants of unknown significance have been identified for RAD51C alone, impairing cancer risk assessment and therapeutic strategies. Here, we interrogated >50 RAD51C missense variants, finding that mutations in residues conserved with RAD51 strongly predicted HR deficiency and disrupted interactions with other RAD51 paralogs. A cluster of mutations was identified in and around the Walker A box that led to impairments in HR, interactions with three other RAD51 paralogs, binding to single-stranded DNA, and ATP hydrolysis. We generated structural models of the two RAD51 paralog complexes containing RAD51C, RAD51B-RAD51C-RAD51D-XRCC2 and RAD51C-XRCC3. Together with our functional and biochemical analyses, the structural models predict ATP binding at the interface of RAD51C interactions with other RAD51 paralogs, similar to interactions between monomers in RAD51 filaments, and explain the failure of RAD51C variants in binding multiple paralogs. Ovarian cancer patients with variants in this cluster showed exceptionally long survival, which may be relevant to the reversion potential of the variants. This comprehensive analysis provides a framework for RAD51C variant classification. Importantly, it also provides insight into the functioning of the RAD51 paralog complexes.

Original languageEnglish (US)
Article numbere2202727119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number38
StatePublished - Sep 20 2022


  • DNA repair
  • Homologous recombination
  • RAD51 paralog
  • RAD51C
  • Variants of unknown significance

ASJC Scopus subject areas

  • General


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