A CRISPR-based base-editing screen for the functional assessment of BRCA1 variants

Area of Science:

• Genetics
• Molecular Biology
• Cancer Research

Background:

• BRCA1 gene mutations significantly elevate breast and ovarian cancer risks.
• Functional assessment of novel BRCA1 variants is challenging for clinical management.
• Accurate variant classification is crucial for patient diagnosis and treatment.

Purpose of the Study:

• To evaluate CRISPR-mediated cytosine base editor (BE3) for functional analysis of BRCA1 variants.
• To identify loss-of-function BRCA1 variants using base-editing screening.
• To demonstrate the utility of base editing for reclassifying variants of uncertain significance (VUSs).

Main Methods:

• Utilized CRISPR-mediated base editing with 745 guide RNAs (gRNAs) targeting all BRCA1 exons.
• Performed high-throughput screening to identify variants affecting BRCA1 function.
• Analyzed specific variants including c.-97C>T, c.154C>T, c.3847C>T, c.5056C>T, and c.4986+5G>A.

Main Results:

• Successfully identified several loss-of-function BRCA1 variants.
• Characterized the functional impact of previously uncharacterized variants.
• Demonstrated CRISPR base editing's capability to detect functional defects in BRCA1.

Conclusions:

• CRISPR-mediated base editing is a powerful tool for functional genomics.
• This technology facilitates the reclassification of BRCA1 variants of uncertain significance (VUSs).
• Improved variant classification aids in better clinical management of hereditary cancer risks.