Related Experiment Video
Updated: Feb 8, 2026

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila
Published on: August 20, 2019
The functional impact of variants of uncertain significance in BRCA2
Romy L S Mesman1, Fabienne M G R Calléja1, Giel Hendriks1
1Department of Human Genetics, Leiden University Medical Center, PO Box 9600, Leiden, 2300RC, The Netherlands.
Purpose:
Genetic testing has uncovered large numbers of variants in the BRCA2 gene for which the clinical significance is unclear. Cancer risk prediction of these variants of uncertain significance (VUS) can be improved by reliable assessment of the extent of impairment of the tumor suppressor function(s) of BRCA2.
Methods:
Here, we evaluated the performance of the mouse embryonic stem cell (mESC)-based functional assay on an extensive set of BRCA2 missense variants.
Results:
Whereas all 20 nonpathogenic (class 1/2) variants were able to complement the cell lethal phenotype induced by loss of endogenous mouse Brca2, only 1 out of 15 pathogenic (class 4/5) variants (p.Gly2609Asp) was able to do so. However, in this variant the major tumor suppressive activity of BRCA2, i.e., homology directed repair (HDR), was severely abrogated. Among 43 evaluated VUS (class 3), 7 were unable to complement the lethal phenotype of mouse Brca2 loss while 7 other variants displayed a more severe reduction of HDR activity than observed for class 1/ 2 variants.
Conclusion:
The mESC-based BRCA2 functional assay can reliably determine the functional impact of VUS, distinguish between pathogenic and nonpathogenic variants, and may contribute to improved cancer risk estimation for BRCA2 VUS carriers.
Related Concept Videos
Histone Variants at the Centromere
Statistical Significance
Significance of Center of Mass
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Cholesterol: Significance and Regulation
Considering cholesterol and...
Significance Testing: Overview

