Characterization of BRCA1 and BRCA2 variants found in a Norwegian breast or ovarian cancer cohort
- 1.1k Downloads
Germline mutations in BRCA1 and BRCA2 cause hereditary breast and ovarian cancer. Molecular screening of these two genes in patients with a family history of breast or ovarian cancer has revealed pathogenic variants as well as genetic variants of unknown significance (VUS). These VUS may cause a challenge in the genetic counseling process regarding clinical management of the patient and the family. We investigated 32 variants previously detected in 33 samples from patients with a family history of breast or ovarian cancer. cDNA was analyzed for alternative transcripts and selected missense variants located in the BRCT domains of BRCA1 were assessed for their trans-activation ability. Although an extensive cDNA analysis was done, only three of the 32 variants appeared to affect the splice-process (BRCA1 c.213-5T>A, BRCA1 c.5434C>G and BRCA2 c.68-7T>A). In addition, two variants located in the BRCT domains of BRCA1 (c.5075A>C p.Asp1692Ala and c.5513T>G p.Val1838Gly) were shown to abolish the BRCT domain trans-activation ability, whereas BRCA1 c.5125G>A p.Gly1709Arg exhibited equal trans-activation capability as the WT domain. These functional studies may offer further insights into the pathogenicity of certain identified variants; however, this assay is only applicable for a subset of missense variants.
KeywordsBRCA1 BRCA2 Cancer cDNA-analysis Functional-assay
We thank Alvaro N. A. Monteiro for kindly providing us with the BRCT containing plasmids necessary for the trans-activation assay. We also thank “Helse Nord” for providing the necessary funding for this study (Grant # SFP1161-14).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All participants gave written informed consent for diagnostic testing. The project was submitted to the appropriate regional ethics committee, however, since the samples were tested diagnostically the regional ethical committee waved the need for ethical approval based on the Norwegian regional health organization law § 2 and § 9 and the Norwegian research ethical law § 4.
- 1.Safran M, Dalah I, Alexander J, et al (2010) GeneCards Version 3: the human gene integrator. Database (Oxford) 2010: baq020 DOI 10.1093/database/baq020
- 16.den Dunnen JT, Antonarakis SE (2000) Mutation nomenclature extensions and suggestions to describe complex mutations: a discussion. Hum Mutat 15(1):7–12. doi: 10.1002/(SICI)1098-1004(200001)15:1<7:AID-HUMU4>3.0.CO;2-N CrossRefGoogle Scholar
- 19.Sequencher® version 5.3 sequence analysis software. Gene Codes Corporation, Ann Arbor, MI USA. http://www.genecodes.com
- 28.Hoya M, Soukarieh O, Lopez-Perolio I et al (2016) Combined genetic and splicing analysis of BRCA1 c.[594-2A>C; 641A>G] highlights the relevance of naturally occurring in-frame transcripts for developing disease gene variant classification algorithms. Hum Mol Genet. doi: 10.1093/hmg/ddw094 PubMedGoogle Scholar
- 39.Lek M, Karczewski K, Minikel E, et al (2015) Analysis of protein-coding genetic variation in 60,706 humans. Biorxiv. doi: 10.1101/030338
- 40.Simard J, Dumont M, Moisan AM et al (2007) Evaluation of BRCA1 and BRCA2 mutation prevalence, risk prediction models and a multistep testing approach in French-Canadian families with high risk of breast and ovarian cancer. J Med Genet 44(2):107–121. doi: 10.1136/jmg.2006.044388 CrossRefPubMedGoogle Scholar
- 44.Bonnet C, Krieger S, Vezain M et al (2008) Screening BRCA1 and BRCA2 unclassified variants for splicing mutations using reverse transcription PCR on patient RNA and an ex vivo assay based on a splicing reporter minigene. J Med Genet 45(7):438–446. doi: 10.1136/jmg.2007.056895 CrossRefPubMedGoogle Scholar
- 52.Scott CL, Jenkins MA, Southey MC et al (2003) Average age-specific cumulative risk of breast cancer according to type and site of germline mutations in BRCA1 and BRCA2 estimated from multiple-case breast cancer families attending Australian family cancer clinics. Hum Genet 112(5–6):542–551. doi: 10.1007/s00439-003-0908-6 PubMedGoogle Scholar