A Multiplex Homology-Directed DNA Repair Assay Reveals the Impact of More Than 1,000 BRCA1 Missense Substitution Variants on Protein Function

Am J Hum Genet. 2018 Oct 4;103(4):498-508. doi: 10.1016/j.ajhg.2018.07.016. Epub 2018 Sep 12.

Abstract

Loss-of-function pathogenic variants in BRCA1 confer a predisposition to breast and ovarian cancer. Genetic testing for sequence changes in BRCA1 frequently reveals a missense variant for which the impact on cancer risk and on the molecular function of BRCA1 is unknown. Functional BRCA1 is required for the homology-directed repair (HDR) of double-strand DNA breaks, a critical activity for maintaining genome integrity and tumor suppression. Here, we describe a multiplex HDR reporter assay for concurrently measuring the effects of hundreds of variants of BRCA1 for their role in DNA repair. Using this assay, we characterized the effects of 1,056 amino acid substitutions in the first 192 residues of BRCA1. Benchmarking these results against variants with known effects on DNA repair function or on cancer predisposition, we demonstrate accurate discrimination of loss-of-function versus benign missense variants. We anticipate that this assay can be used to functionally characterize BRCA1 missense variants at scale, even before the variants are observed in results from genetic testing.

Keywords: BRCA1; DNA repair; VUS; missense variants; variants of uncertain significance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • BRCA1 Protein / genetics*
  • Cell Line, Tumor
  • DNA / genetics
  • DNA Breaks, Double-Stranded
  • DNA Repair / genetics*
  • Genetic Predisposition to Disease / genetics
  • Genetic Testing / methods
  • HeLa Cells
  • Humans
  • Mutation, Missense / genetics*
  • Neoplasms / genetics

Substances

  • BRCA1 Protein
  • BRCA1 protein, human
  • DNA