1263P - BRCA1 large gene rearrangements (LGRs) in Russian breast cancer patients: the development of the droplet digital PCR assay for LGR detection and th...

Date 11 September 2017
Event ESMO 2017 Congress
Session Poster display session
Topics Cancer in Adolescents
Diagnostics
Breast Cancer
Translational Research
Presenter Evgeny Imyanitov
Citation Annals of Oncology (2017) 28 (suppl_5): v449-v452. 10.1093/annonc/mdx378
Authors E. Imyanitov1, E. Preobrazhenskaya1, I. Bizin2, E. Kuligina1, E. Anisimova3, S. Laptiyev4, E. Suspitsin1, S. Aleksakhina1, A. Togo1, A. Sokolenko1
  • 1Department Of Tumor Biology, N.N. Petrov Institute of Oncology, 197758 - St.-Petersburg/RU
  • 2Laboratory Of Bioinformatics, Polytechnical University, 195251 - St.-Petersburg/RU
  • 3Outpatient Clinic, Leningrad Regional Oncology Dispensary, 191104 - Saint Petersburg/RU
  • 4Department Of Medical Biology And Genetics, I.P. Pavlov Medical University, 197022 - St.-Petersburg/RU

Abstract

Background

Some pathogenic BRCA1 mutations are represented by large gene rearrangements (LGRs). LGRs cannot be detected by conventional Sanger sequencing. Multiplex ligation-dependent probe amplification (MLPA) is a leading method for LGR detection, however it is entirely based on the use of commercial kits, includes relatively lengthy hybridization step and is poorly suitable for the large-scale screening for recurrent deletions.

Methods

We developed and validated the droplet digital PCR (ddPCR) assay, which covers the entire coding region of BRCA1 gene and is capable to precisely quantitate the copy number for each exon.

Results

141 breast cancer (BC) patients, who demonstrated evident clinical features of hereditary BC but turned out to be BRCA1/2 mutation-negative upon Sanger sequencing, were subjected to the LGR analysis. 4 patients with LGR were identified, with 3 cases of exon 8 deletion and 1 women carrying the deletion of exons 3-7. Excellent concordance with MLPA was observed. Exon 8 copy number was tested in additional 720 high-risk BC, and another 3 cases with the deletion were revealed; MLPA re-analysis demonstrated that exon 8 loss was a part of a larger genetic alteration in 2 cases, while the remaining patient had isolated defect of exon 8. Long-range PCR and next generation sequencing revealed, that 3 out of 4 samples with isolated exon 8 deletion had an identical rearrangement.

Conclusions

Droplet digital PCR is a reliable tool for detection of large gene rearrangements. BRCA1 LGRs are rare in Russian hereditary BC patients, with exon 8 deletion being a recurrent allele in this population.

Clinical trial identification

Legal entity responsible for the study

Laboratory of Molecular Oncology, N.N. Petrov Institute of Oncology, St.-Petersburg

Funding

Russian Science Foundation (grant 14-25-00111)

Disclosure

All authors have declared no conflicts of interest.