Alternative titles; symbols
HGNC Approved Gene Symbol: RAD51C
Cytogenetic location: 17q22 Genomic coordinates (GRCh38): 17:58,692,573-58,735,611 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 17q22 | {Breast-ovarian cancer, familial, susceptibility to, 3} | 613399 | 3 | |
| Fanconi anemia, complementation group O | 613390 | Autosomal recessive | 3 |
The RAD51 family of related genes, identified in both yeast and humans, encode strand-transfer proteins thought to be involved in recombinational repair of DNA damage and in meiotic recombination. Several members of the mammalian RAD51 gene family have been identified; see, for example, RAD51A (179617), RAD51B (602948), XRCC3 (600675), and DMC1 (602721) (summary by Dosanjh et al., 1998).
Dosanjh et al. (1998) isolated and characterized a novel member of the RAD51 family, which they designated RAD51C. The authors identified several clones with amino acid similarity to the human XRCC3 and yeast Rad51 proteins by screening an EST database. They then isolated a full-length RAD51C cDNA from a human leukocyte cDNA library. The RAD51C cDNA encodes a predicted 376-amino acid protein that has 18 to 26% amino acid identity with other members of the human RAD51 family. By Northern blot analysis, Dosanjh et al. (1998) showed that RAD51C is expressed as an approximately 1.3-kb mRNA in a variety of human tissues, with highest expression in testis, heart muscle, spleen and prostate. Using a yeast 2-hybrid system, they demonstrated that the RAD51C protein interacts strongly with RAD51B and moderately with XRCC3, but not with itself.
Sage et al. (2010) noted that the N terminus of RAD51C contains a putative mitochondria targeting sequence.
As a first step in understanding the roles of the RAD51 paralogs in recombination, Masson et al. (2001) overexpressed the human RAD51C and XRCC3 (600675) proteins and purified them from baculovirus-infected insect cells. The 2 proteins copurified as a complex, a property that reflects their endogenous association observed in HeLa cells. The purified RAD51C-XRCC3 complex bound single-stranded, but not duplex, DNA to form protein-DNA networks that could be visualized by electron microscopy.
Liu et al. (2004) demonstrated that extracts from cells carrying mutations in the recombination/repair genes RAD51C or XRCC3 have reduced levels of Holliday junction resolvase activity. Moreover, depletion of RAD51C from fractionated human extracts caused a loss of branch migration and resolution activity, but these functions were restored by complementation with a variety of RAD51 paralog complexes containing RAD51C. Liu et al. (2004) concluded that RAD51 paralogs are involved in Holliday junction processing in human cells.
Using Western blot analysis, Sage et al. (2010) found that mitochondrial levels of RAD51, RAD51C, and XRCC3 in human cell lines increased in response to oxidative stress and weak ionizing radiation. Immunoprecipitation analysis showed that oxidative stress increased the interaction of RAD51 with mitochondrial DNA (mtDNA) Oxidative stress normally increases mtDNA copy number; however, knockdown of RAD51, RAD51C, or XRCC3 suppressed this stress response and resulted in decreased mtDNA copy number. Sage et al. (2010) concluded that proteins of the homologous recombination pathway are required to maintain the mitochondrial genome.
Adelman et al. (2013) reported that Helq (606769) helicase-deficient mice exhibit subfertility, germ cell attrition, interstrand crosslink (ICL) sensitivity, and tumor predisposition, with Helq heterozygous mice exhibiting a similar, albeit less severe, phenotype than the null, indicative of haploinsufficiency. Adelman et al. (2013) established that HELQ interacts directly with the RAD51 paralog complex BCDX2 (RAD51B, RAD51C, RAD51D, 602954; and XRCC2, 600375) and functions in parallel to the Fanconi anemia pathway to promote efficient homologous recombination at damaged replication forks. Adelman et al. (2013) concluded that their results revealed a critical role for HELQ in replication-coupled DNA repair, germ cell maintenance, and tumor suppression in mammals.
Dosanjh et al. (1998) noted that a previously identified STS (GenBank G20939) from within RAD51C had been mapped to distal 17q.
Vaz et al. (2010) mapped the RAD51C gene to chromosome 17q21-q24 by autozygosity mapping.
Fanconi Anemia, Complementation Group O
By genomewide autozygosity mapping followed by candidate gene sequencing in a Pakistani family with Fanconi anemia (FANCO; 613390), Vaz et al. (2010) identified a homozygous mutation in the RAD51C gene (R258H; 602774.0001). In vitro functional studies showed that the mutation resulted in loss of RAD51 focus formation in response to DNA damage, and that the defect could be rescued by expression of wildtype RAD51C.
Familial Breast-Ovarian Cancer Susceptibility 3
Meindl et al. (2010) identified 6 different monoallelic (heterozygous) pathogenic mutations in the RAD51C gene (e.g., 602774.0002-602774.0004) in 6 (1.3%) of 480 unrelated women from pedigrees with breast and ovarian cancer-3 (BROVCA3; 613399). There were 2 frameshift insertions, 2 splice site mutations, and 2 nonfunctional missense mutations. RAD51C mutations were not found in 620 pedigrees with breast cancer only or in 2,912 healthy German controls. Analysis of tumor tissue showed loss of heterozygosity at the RAD51C locus, and in vitro studies showed that the mutant proteins were unable to restore normal RAD51C activity to RAD51C-deficient cells. These findings were consistent with RAD51C acting as a tumor suppressor gene. Meindl et al. (2010) concluded that the results supported the 'common disease, rare allele' hypothesis for cancer.
Pelttari et al. (2011) identified 2 recurrent mutations in the RAD51C gene (602774.0007 and 602774.0008) in Finnish patients with breast-ovarian cancer. The mutations associated with an increased risk of familial breast and ovarian cancer (odds ratio (OR) of 13.59; p = 0.026 compared to controls), but especially with familial ovarian cancer in the absence of breast cancer (OR of 213; p = 0.0002). The mutations also associated with unselected ovarian cancer (OR of 6.31; p = 0.033), but there was a significantly higher mutation rate among the familial cases. However, no mutations were found among cases with familial breast cancer only, and the mutation frequency among all breast cancer cases was not different from controls. The results suggested that RAD51C is a moderate to high risk susceptibility gene for ovarian cancer.
Thompson et al. (2012) identified 2 truncating mutations in the RAD51C gene (see, e.g., 602774.0005) in 2 of 335 families with breast-ovarian cancer or ovarian cancer only. One of 267 additional patients with ovarian cancer was found to carry another truncating mutation (602774.0006). No RAD51C mutations were found in 1,053 families with breast cancer only. The findings suggested a low frequency (less than 1%) of RAD51C mutations in families with increased risk of ovarian cancer, particularly in the context of breast cancer.
Among 1,132 probands from families with a history of ovarian cancer occurring with or without breast cancer and 272 individuals with ovarian cancer from a hospital-based unselected case series, Loveday et al. (2012) identified 12 truncating mutations in the RAD51C gene. Nine of the mutations occurred in familial cases, but segregation with disease was not proven in any of the families. One mutation was also found in 1 of 1,156 controls. The relative risk of ovarian cancer for RAD51C mutation carriers was estimated to be 5.88 (p = 7.65 x 10(-7)). In contrast, there was no evidence of an association with breast cancer (relative risk = 0.91, p = 0.8).
In affected members of a consanguineous Pakistani family with Fanconi anemia, complementation group O (FANCO; 613390), Vaz et al. (2010) identified a homozygous 773G-A transition in exon 5 of the RAD51C gene, resulting in an arg258-to-his (R258H) substitution in a highly conserved residue. Structural analysis indicated that the affected residue is located between 2 alpha helices, and that the mutation may disrupt hydrogen bond interactions, resulting in perturbations of secondary structure. However, the mutant protein was detectable on protein blot analysis, indicating that the stability was unaffected. In vitro studies of patient fibroblasts showed increased chromosomal breakage after exposure to interstrand cross-linking agents, with pronounced arrest of the cell cycle at G2 associated with impaired RAD51 (179617) focus formation. The defect was rescued by wildtype RAD51C. The R258H mutation caused a defect downstream of the monoubiquitination of FANCD2 (227646) and FANCI (611360), thus affecting the step of homologous recombination during DNA repair. Some cellular studies showed that the R258H mutation may be a hypomorphic allele. Each unaffected parent was heterozygous for the mutation, which was not found in 47 ethnically matched controls.
In 3 women from a German family with breast-ovarian cancer-3 (BROVCA3; 613399), Meindl et al. (2010) identified a germline heterozygous G-to-T transversion in intron 5 of the RAD51C gene (904+5G-T), resulting in a splice site mutation and the skipping of exon 6, which was confirmed by mRNA studies. Two individuals had breast cancer at ages 44 and 36 years, respectively, and the third had ovarian cancer at age 81 years. Tumor tissue available from 2 of the patients showed loss of heterozygosity at the RAD51C locus. The mutation was not found in 2,912 controls.
In 3 women from a German family with breast-ovarian cancer-3 (613399), Meindl et al. (2010) identified a germline heterozygous 374G-T transversion in exon 2 of the RAD51C gene, resulting in a gly125-to-val (G125V) substitution. Two individuals had breast cancer at ages 45 and 33 years, respectively, and the third had breast cancer at age 63 and ovarian cancer at age 65. Tumor tissue available from all tumors showed loss of heterozygosity at the RAD51C locus. The mutation was not found in 2,912 controls. In vitro studies showed that the G125V mutant was unable to restore normal RAD51C activity to RAD51C-deficient cells.
In 3 women from a German family with breast-ovarian cancer-3 (613399), Meindl et al. (2010) identified a germline heterozygous 414G-C transversion in exon 3 of the RAD51C gene, resulting in a leu138-to-phe (L138F) substitution. Two individuals had ovarian cancer at age 53 years, and the third had breast cancer in her early fifties. Tumor tissue available from all tumors showed loss of heterozygosity at the RAD51C locus. There was a history of other cancers in 3 deceased female family members. The mutation was not found in 2,912 controls. In vitro studies showed that the L138F mutant was unable to restore normal RAD51C activity to RAD51C-deficient cells.
In 3 affected women from a family with breast-ovarian cancer-3 (613399), Thompson et al. (2012) identified a heterozygous 397C-T transition in exon 2 of the RAD51C gene, resulting in a gln133-to-ter (Q133X) substitution. The mutation was not found in 427 controls. The family was part of a larger cohort of 314 families with breast-ovarian cancer. The mutation was also found in 2 additional family members with colorectal cancer.
Loveday et al. (2012) identified a Q133X mutation in a patient with ovarian cancer and in an unrelated patient with breast cancer. The patient with ovarian cancer had 2 deceased relatives with ovarian cancer, but these patients were not studied genetically. The patient with breast cancer had a deceased sister with breast cancer and a deceased mother with ovarian cancer, but these patients were not studied genetically.
In a patient with breast-ovarian cancer-3 (613399), Thompson et al. (2012) identified a heterozygous 1-bp deletion (230delG) in exon 2 of the RAD51C gene, resulting in a frameshift and premature termination (Gly77ValfsTer24). The mutation was not found in 427 controls. No family history was available.
In 3 women from a Finnish family with breast-ovarian cancer-3 (613399), Pelttari et al. (2011) identified a heterozygous 1-bp deletion (93delG) in exon 1 of the RAD51C gene, resulting in a frameshift and premature termination (Phe32SerfsTer8). The deletion was also found in 2 additional family members with skin cancer (1 male and 1 female) and in 2 unaffected male family members. A woman with ovarian cancer from another Finnish family was also found to carry the 93delG mutation. Her mother, who had ovarian cancer, was not available for study. Three unaffected family members, 2 of whom were women, also carried the mutation. These 2 families were part of a larger cohort of 277 Finnish families with breast or ovarian cancer. Screening of additional cohorts identified the 93delG mutation in 2 of 409 unselected ovarian cancer patients and in 2 (0.2%) of 1,279 controls. The mutation was also found in 2 of 686 unselected breast cancer patients from the Tampere region of Finland, but not in 807 controls from this region.
Pelttari et al. (2011) identified a G-to-A transition in intron 5 of the RAD51C gene (837+1G-A) in 2 of 277 Finnish families with breast-ovarian cancer (613399). The mutation was also found in 2 of 409 unselected ovarian cancer patients, but not in 1,279 controls. The transition was demonstrated to result in a splice site mutation and the formation of 2 mutant transcripts.
Adelman, C. A., Lolo, R. L., Birkbak, N. J., Murina, O., Matsuzaki, K., Horejsi, Z., Parmar, K., Borel, V., Skehel, J. M., Stamp, G., D'Andrea, A., Sartori, A. A., Swanton, C., Boulton, S. J. HELQ promotes RAD51 paralogue-dependent repair to avert germ cell loss and tumorigenesis. Nature 502: 381-384, 2013. [PubMed: 24005329] [Full Text: https://doi.org/10.1038/nature12565]
Dosanjh, M. K., Collins, D. W., Fan, W., Lennon, G. G., Albala, J. S., Shen, Z., Schild, D. Isolation and characterization of RAD51C, a new human member of the RAD51 family of related genes. Nucleic Acids Res. 26: 1179-1184, 1998. [PubMed: 9469824] [Full Text: https://doi.org/10.1093/nar/26.5.1179]
Liu, Y., Masson, J.-Y., Shah, R., O'Regan, P., West, S. C. RAD51C is required for Holliday junction processing in mammalian cells. Science 303: 243-246, 2004. [PubMed: 14716019] [Full Text: https://doi.org/10.1126/science.1093037]
Loveday, C., Turnbull, C., Ruark, E., Xicola, R. M. M., Ramsay, E., Hughes, D., Warren-Perry, M., Snape, K., Breast Cancer Susceptibility Collaboration (BCSC) (UK), Eccles, D., Evans, D. G., Gore, M., Renwick, A., Seal, S., Antoniou, A. C., Rahman, N. Germline RAD51C mutations confer susceptibility to ovarian cancer. (Letter) Nature Genet. 44: 475-476, 2012. [PubMed: 22538716] [Full Text: https://doi.org/10.1038/ng.2224]
Masson, J.-Y., Stasiak, A. Z., Stasiak, A., Benson, F. E., West, S. C. Complex formation by the human RAD51C and XRCC3 recombination repair proteins. Proc. Nat. Acad. Sci. 98: 8440-8446, 2001. [PubMed: 11459987] [Full Text: https://doi.org/10.1073/pnas.111005698]
Meindl, A., Hellebrand, H., Wiek, C., Erven, V., Wappenschmidt, B., Niederacher, D., Freund, M., Lichtner, P., Hartmann, L., Schaal, H., Ramser, J., Honisch, E., and 12 others. Germline mutations in breast and ovarian cancer pedigrees establish RAD51C as a human cancer susceptibility gene. Nature Genet. 42: 410-414, 2010. [PubMed: 20400964] [Full Text: https://doi.org/10.1038/ng.569]
Pelttari, L. M., Heikkinen, T., Thompson, D., Kallioniemi, A., Schleutker, J., Holli, K., Blomqvist, C., Aittomaki, K., Butzow, R., Nevanlinna, H. RAD51C is a susceptibility gene for ovarian cancer. Hum. Molec. Genet. 20: 3278-3288, 2011. [PubMed: 21616938] [Full Text: https://doi.org/10.1093/hmg/ddr229]
Sage, J. M., Gildemeister, O. S., Knight, K. L. Discovery of a novel function for human Rad51: maintenance of the mitochondrial genome. J. Biol. Chem. 285: 18984-18990, 2010. [PubMed: 20413593] [Full Text: https://doi.org/10.1074/jbc.M109.099846]
Thompson, E. R., Boyle, S. E., Johnson, J., Ryland, G. L., Sawyer, S., Choong, D. Y. H., kConFab, Chenevix-Trench, G., Trainer, A. H., Lindeman, G. J., Mitchell, G., James, P. A., Campbell, I. G. Analysis of RAD51C germline mutations in high-risk breast and ovarian cancer families and ovarian cancer patients. Hum. Mutat. 33: 95-99, 2012. [PubMed: 21990120] [Full Text: https://doi.org/10.1002/humu.21625]
Vaz, F., Hanenberg, H., Schuster, B., Barker, K., Wiek, C., Erven, V., Neveling, K., Endt, D., Kesterton, I., Autore, F., Fraternali, F., Freund, M., Hartmann, L., Grimwade, D., Roberts, R. G., Schaal, H., Mohammed, S., Rahman, N., Schindler, D., Mathew, C. G. Mutation of the RAD51C gene in a Fanconi anemia-like disorder. Nature Genet. 42: 406-409, 2010. [PubMed: 20400963] [Full Text: https://doi.org/10.1038/ng.570]