Dataset Information

Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study.

ABSTRACT: Nearly one-half of BRCA1 and BRCA2 sequence variations are variants of uncertain significance (VUSs) and are candidates for splice alterations for example, by disrupting/creating splice sites. As out-of-frame splicing defects lead to a marked reduction of the level of the mutant mRNA cleared through nonsense-mediated mRNA decay, a cDNA-based test was developed to show the resulting allelic imbalance (AI). Fifty-four VUSs identified in 53 hereditary breast/ovarian cancer (HBOC) patients without BRCA1/2 mutation were included in the study. Two frequent exonic single-nucleotide polymorphisms on both BRCA1 and BRCA2 were investigated by using a semiquantitative single-nucleotide primer extension approach and the cDNA allelic ratios obtained were corrected using genomic DNA ratios from the same sample. A total of five samples showed AI. Subsequent transcript analyses ruled out the implication of VUS on AI and identified a deletion encompassing BRCA2 exons 12 and 13 in one sample. No sequence abnormality was found in the remaining four samples, suggesting implication of cis- or trans-acting factors in allelic expression regulation that might be disease causative in these HBOC patients. Overall, this study showed that AI screening is a simple way to detect deleterious splicing defects and that a major role for VUSs and deep intronic mutations in splicing anomalies is unlikely in BRCA1/2 genes. Methods to analyze gene expression and identify regulatory elements in BRCA1/2 are now needed to complement standard approaches to mutational analysis.

SUBMITTER: Caux-Moncoutier V

PROVIDER: S-EPMC2986693 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study.

Caux-Moncoutier Virginie V Pagès-Berhouet Sabine S Michaux Dorothée D Asselain Bernard B Castéra Laurent L De Pauw Antoine A Buecher Bruno B Gauthier-Villars Marion M Stoppa-Lyonnet Dominique D Houdayer Claude C

European journal of human genetics : EJHG 20090527 11

Nearly one-half of BRCA1 and BRCA2 sequence variations are variants of uncertain significance (VUSs) and are candidates for splice alterations for example, by disrupting/creating splice sites. As out-of-frame splicing defects lead to a marked reduction of the level of the mutant mRNA cleared through nonsense-mediated mRNA decay, a cDNA-based test was developed to show the resulting allelic imbalance (AI). Fifty-four VUSs identified in 53 hereditary breast/ovarian cancer (HBOC) patients without B ...[more]

PMID: 19471317

Similar Datasets

Project description:Clinical genetic testing for hereditary breast and ovarian cancer (HBOC) is becoming widespread. However, the interpretation of variants of unknown significance (VUS) in HBOC genes, such as the clinically actionable genes BRCA1 and BRCA2, remain a challenge. Among the variants that are frequently classified as VUS are those with unclear effects on splicing. In order to address this issue we developed a high-throughput RNA-massively parallel sequencing assay-CloneSeq-capable to perform quantitative and qualitative analysis of transcripts in cell lines and HBOC patients. This assay is based on cloning of RT-PCR products followed by massive parallel sequencing of the cloned transcripts. To validate this assay we compared it to the RNA splicing assays recommended by members of the ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) consortium. This comparison was performed using well-characterized lymphoblastoid cell lines (LCLs) generated from carriers of the BRCA1 or BRCA2 germline variants that have been previously described to be associated with splicing defects. CloneSeq was able to replicate the ENIGMA results, in addition to providing quantitative characterization of BRCA1 and BRCA2 germline splicing alterations in a high-throughput fashion. Furthermore, CloneSeq was used to analyze blood samples obtained from carriers of BRCA1 or BRCA2 germline sequence variants, including the novel uncharacterized alteration BRCA1 c.5152+5G>T, which was identified in a HBOC family. CloneSeq provided a high-resolution picture of all the transcripts induced by BRCA1 c.5152+5G>T, indicating it results in significant levels of exon skipping. This analysis proved to be important for the classification of BRCA1 c.5152+5G>T as a clinically actionable likely pathogenic variant. Reclassifications such as these are fundamental in order to offer preventive measures, targeted treatment, and pre-symptomatic screening to the correct individuals.

Project description:ImportanceThe clinical importance of genetic testing of BRCA1 and BRCA2 in breast, ovarian, prostate, and pancreatic cancers is widely recognized. However, there is insufficient evidence to include other cancer types that are potentially associated with BRCA1 and BRCA2 in clinical management guidelines.ObjectiveTo evaluate the association of BRCA1 and BRCA2 pathogenic variants with additional cancer types and their clinical characteristics in 100 914 individuals across 14 cancer types.Design, setting, and participantsThis case-control analysis to identify cancer types and clinical characteristics associated with pathogenic variants in BRCA1 and BRCA2 included DNA samples and clinical information from 63 828 patients with 14 common cancer types and 37 086 controls that were sourced from a multi-institutional hospital-based registry, BioBank Japan, between April 2003 and March 2018. The data were analyzed between August 2019 and October 2021.Main outcomes and measuresGermline pathogenic variants in coding regions and 2 bp flanking intronic sequences in BRCA1 and BRCA2 were identified by a multiplex polymerase chain reaction-based target sequence method. Associations of (likely) pathogenic variants with each cancer type were assessed by comparing pathogenic variant carrier frequency between patients in each cancer type and controls.ResultsA total of 65 108 patients (mean [SD] age at diagnosis, 64.1 [11.6] years; 27 531 [42.3%] female) and 38 153 controls (mean [SD] age at registration, 61.8 [14.6] years; 17 911 [46.9%] female) were included in this study. A total of 315 unique pathogenic variants were identified. Pathogenic variants were associated with P < 1 × 10-4 with an odds ratio (OR) of greater than 4.0 in biliary tract cancer (OR, 17.4; 95% CI, 5.8-51.9) in BRCA1, esophageal cancer (OR, 5.6; 95% CI, 2.9-11.0) in BRCA2, and gastric cancer (OR, 5.2; 95% CI, 2.6-10.5) in BRCA1, and (OR, 4.7; 95% CI, 3.1-7.1) in BRCA2 in addition to the 4 established cancer types. We also observed an association with 2 and 4 other cancer types in BRCA1 and BRCA2, respectively. Biliary tract, female breast, ovarian, and prostate cancers showed enrichment of carrier patients according to the increased number of reported cancer types in relatives.Conclusions and relevanceThe results of this large-scale registry-based case-control study suggest that pathogenic variants in BRCA1 and BRCA2 were associated with the risk of 7 cancer types. These results indicate broader clinical relevance of BRCA1 and BRCA2 genetic testing.

Dataset Information

Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study.

Publications

Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets