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Functional characterization of BRCA1 sequence variants using a yeast small colony phenotype assay
Robert S Coyne1, Heather B McDonald, Keith Edgemon
1Department of Biochemistry and Molecular Genetics, University of Virginia Health Sciences Center, Charlottesville, Virginia, USA. rcoyne@nsf.gov
Cancer Biology & Therapy
|March 9, 2004
Summary
The yeast small colony phenotype (SCP) assay shows promise for evaluating BRCA1 missense variants, particularly within the BRCT repeats, aiding in cancer risk assessment.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- Germline mutations in the BRCA1 tumor suppressor gene increase breast and other cancer risks.
- The functional impact of many BRCA1 missense variants remains unclear.
- Predictive assays are needed to differentiate pathogenic variants from benign polymorphisms.
Purpose of the Study:
- To evaluate the utility of the yeast small colony phenotype (SCP) assay for characterizing BRCA1 missense variants.
- To assess the assay's ability to identify cancer-predisposing mutations.
Main Methods:
- Constructed 28 missense mutations in the C-terminal region of BRCA1.
- Expressed mutated BRCA1 proteins in yeast (Saccharomyces cerevisiae).
- Evaluated variant function using the SCP assay.
Main Results:
- The SCP assay showed no evidence of identifying inactivating mutations upstream of the BRCT repeats.
- Results within and between BRCT repeats generally agreed with structural modeling and other functional assays.
- The assay provided confirmatory in vivo evidence for some BRCA1 missense variants.
Conclusions:
- The yeast SCP assay can aid in characterizing some BRCA1 missense variants, particularly those within the BRCT repeats.
- The assay provides valuable in vivo data for variant interpretation.
- Further validation is needed for mutations outside the BRCT repeats.