Abstract 4664
Background
BRCA1 and BRCA2 are the genes most frequently associated with hereditary breast and ovarian cancer (HBOC). Besides point mutations, BRCA1/2 large genomic rearrangements (LGR) have been observed, with different frequencies in specific populations. This study aims to update the frequency of BRCA1 and BRCA2 LGR in our population, as well as to characterize the gene distribution of these genetic events.
Methods
All high risk pts referred to our multidisciplinary program between 2000-2018 that consented on genetic testing were reviewed for BRCA1 and BRCA2 point pathogenic variants (several methodologies throughout the years including Conformation Sensitive Gel Electrophoresis; Conformation Sensitive Capillary Electrophoresis; Sanger Sequencing and Next Generation Sequencing) and LGR with Multiplex Ligation dependent Probe Amplification (MLPA).
Results
3763 of 3901 index pts consented on genetic testing and 473 pts had 476 different pathogenic variants (PV). In 3 cases double germline PV were observed: BRCA1 (c.68_69delAG) and CHEK2 [c.(908 + 1_909-1)_(1095 + 1_1096-1)del]; ATM (c.8264_8268delATAAG) and PALB2 (c.751C>T); BRCA2 (c.156_157insAlu) and CHEK2 (c.593-1G>T). BRCA1 PV were detected in 151 pts with 24 LGR of these (15,9%) being detected by MLPA. The most frequent BRCA1 LGR was c. (4185 + 1_4186-1)_(4357 + 1_4358-1)dup (n = 8). BRCA2 PV were detected in 260 pts with 99 LGR: 92 pts with the Portuguese founder mutation c.156_157insAlu (detected by specific PCR or MLPA) and 7 pts with other LGR (detected by MLPA). The second most frequent BRCA2 LGR was c. (8632 + 1_8633-1)_(8754 + 1_8755-1)dup (n = 5). Nine CHEK2 PV were detected with the SALSA MLPA probemix P045 BRCA2/CHEK2: c.1100delC (8 pts) and c. (908 + 1_909-1)_(1095 + 1_1096-1)del (1pt). The total percentage of BRCA1 and BRCA2 LGR in our cohort was 26%. Excluding the Portuguese founder mutation c.156_157insAlu, the prevalence of LGR was 6,5%.
Conclusions
There is a high prevalence of LGR in the Portuguese population, mostly because of the Portuguese founder mutation c.156_157insAlu. Even if excluding this event, other LRG still account for 6,5% of the BRCA1 and BRCA2 pathogenic variants. These results emphasize the importance of testing LGR in all patients with high risk HBOC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
3181 - Effects of Three Products in the Prevention and Treatment of Chemotherapy and Radiation Therapy-Induced Oral Mucositis
Presenter: Francesca Zannier
Session: Poster Display session 1
Resources:
Abstract
2433 - Boiling Histotripsy-induced Mechanical Ablation Modulates Tumour Microenvironment by Promoting Immunogenic Cell Death of Cancers
Presenter: Cheol-Hee Shin
Session: Poster Display session 1
Resources:
Abstract
2663 - The bacterial receptor NOD2 mediates LGR5+ intestinal stem cells protection against irradiation via mitophagy activation
Presenter: Antonin Levy
Session: Poster Display session 1
Resources:
Abstract
3213 - Pulse mode irradiation regimen of PDT results in high progression free and overall survival in mice with model tumor
Presenter: Alexey Bogdanov
Session: Poster Display session 1
Resources:
Abstract
3722 - Proton-sensitizing effect of small molecule inhibitor of P300 histone acetyltransferase C646 in human pancreatic cancer cells.
Presenter: Sungwon Shin
Session: Poster Display session 1
Resources:
Abstract
5805 - Red-Blood-Cell-Membrane-Enveloped Magnetic Nanoclusters as a Biomimetic Theranostic Nanoplatform for Bimodal Imaging Guided Cancer Photothermal Therapy
Presenter: sheng wang
Session: Poster Display session 1
Resources:
Abstract
5251 - Urine cell-free and extracellular vesicle cargo miRNAs as biomarkers for prostate cancer diagnosis
Presenter: Ivan Zaporozhchenko
Session: Poster Display session 1
Resources:
Abstract
3657 - Parkin, APEX1 and BCL2L1 Tissue Expression in Southern Brazilian Patients with Different Breast Cancer Molecular Subtypes
Presenter: Bianca Cabral
Session: Poster Display session 1
Resources:
Abstract
2839 - Obesity and prognosis in breast cancer
Presenter: Noha Ibrahim
Session: Poster Display session 1
Resources:
Abstract
5132 - SIPA1 is a modulator of HGF induced tumor metastasis via the regulation of tight junctions in lung adenocarcinoma cells
Presenter: Chang Liu
Session: Poster Display session 1
Resources:
Abstract