Identification and Characterization of a New BRCA2 Rearrangement in an Italian Family with Hereditary Breast and
Paola Concolino1, Roberta Rizza2, Karl Hackmann3,4,5,6
1Polo Scienze per Immagini, di Laboratorio e Infettivologiche, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario Agostino Gemelli, Largo Francesco Vito, 1-00168, Rome, Italy. paola.concolino@policlinicogemelli.it.
Introduction:
Many studies document the involvement of BRCA1/2 gene rearrangements in genetic predisposition to breast and ovarian cancer. Large genomic rearrangements (LGRs) of BRCA1 account for 0-27% of all disease-causing mutations in various populations, while LGRs in BRCA2 are rarer. Here, we describe a novel BRCA2 LGR, involving the duplication of exons 4-26, in an Italian family with hereditary breast and ovarian cancer (HBOC) syndrome.
Objective:
Our purpose was to provide an effective characterization of this variant using a combination of different methods able to establish the exact breakpoints of the duplication.
Methods:
A multiplex amplicon quantification (MAQ) assay was used as the primary screening method in the detection of LGRs. Array comparative genomic hybridization (CGH), reverse transcriptase polymerase chain reaction (RT-PCR) and long-range PCR were used for the careful characterization of the rearrangement and breakpoint regions. The Repeat Masker program was employed to identify Alu sequences at breakpoint junctions.
Results:
Array CGH and long-range PCR strategies revealed that the BRCA2 exons 4-26 duplication (g.12016_87170dup) involved exactly 75,154 bp nucleotides between intron 3 and intron 26 of the gene. Given that no Alu repeats were found at the junction sites, we support the hypothesis that the new duplication could be the result of a microhomology-mediated event (MH) involving very short homologous sequences at an upstream breakpoint.
Discussion:
LGR investigation is mandatory in BRCA1/2 routine testing in order to provide a complete result for a targeted therapeutic decision. Nevertheless, the characterization and classification of novel BRCA1/2 variants represents a crucial step in the support of genetic counselling. Our results, including a comprehensive co-segregation analysis, indicate that the novel duplication identifed has a pathogenic role and would be considered a causing-disease variant in genetic and oncologic counselling.
More Related Videos
09:24Silencing of BRCA2 to Identify Novel BRCA2-regulated Biological Functions in Cultured Human Cells
Published on: August 12, 2015
13:04In Vivo and Ex Vivo Approaches to Study Ovarian Cancer Metastatic Colonization of Milky Spot Structures in Peritoneal Adipose
Published on: October 14, 2015
