# XRCC3

Source: https://onco.cc/targets/xrcc3/  
OnCo record `xrcc3` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

XRCC3 (DNA repair protein XRCC3) is a gene. The public catalogues list it as a drug target, a biomarker and a DNA repair gene, and clinical evidence ties its variants to diagnosis, prognosis or drug response. Tied to Triple-negative breast cancer.

## Summary

Involved in the homologous recombination repair (HRR) pathway of double-stranded DNA, thought to repair chromosomal fragmentation, translocations and deletions. Part of the RAD51 paralog protein complex CX3 which acts in the BRCA1-BRCA2-dependent HR pathway. Upon DNA damage, CX3 acts downstream of RAD51 recruitment; the complex binds predominantly to the intersection of the four duplex arms of the Holliday junction (HJ) and to junctions of replication forks.

CIViC holds 1 clinical evidence item and 0 assertions across 1 variant, naming Cisplatin.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: X-ray repair cross complementing 3; DNA repair protein XRCC3
- Tags: cancer-genes-wave
- Symbol: XRCC3
- Class: other
- Biology: Involved in the homologous recombination repair (HRR) pathway of double-stranded DNA, thought to repair chromosomal fragmentation, translocations and deletions. Part of the RAD51 paralog protein complex CX3 which acts in the BRCA1-BRCA2-dependent HR pathway. Upon DNA damage, CX3 acts downstream of RAD51 recruitment; the complex binds predominantly to the intersection of the four duplex arms of the Holliday junction (HJ) and to junctions of replication forks. Involved in HJ resolution and thus in processing HR intermediates late in the DNA repair process; the function may be linked to the CX3 complex and seems to involve GEN1 during mitotic cell cycle progression. Part of a PALB2-scaffolded HR complex containing BRCA2 and RAD51C and which is thought to play a role in DNA repair by HR. Plays a role in regulating mitochondrial DNA copy number under conditions of oxidative stress in the presence of RAD51 and RAD51C. Location: Nucleus; Cytoplasm; Cytoplasm, perinuclear region; Mitochondrion (UniProt). Locus 14q32.33 (HGNC).
- Where found: Triple-negative breast cancer: CIViC evidence names this disease

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: CIViC lists 1 therapies; CIViC holds 1 clinical evidence items on its variants; UniProt keyword "DNA repair". Evidence tier "clinical-evidence" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:12830: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:12830
- UniProt O43542: https://www.uniprot.org/uniprotkb/O43542/entry
- NCBI Gene 7517: https://www.ncbi.nlm.nih.gov/gene/7517
- Ensembl ENSG00000126215: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000126215

## Connected records

- collections: [CIViC](https://onco.cc/collections/civic/)
- cancers: [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)

---
JSON: https://onco.cc/api/v1/entities/xrcc3.json