Email updates

Keep up to date with the latest news and content from BMC Medical Genetics and BioMed Central.

Open Access Research article

High occurrence of BRCA1 intragenic rearrangements in hereditary breast and ovarian cancer syndrome in the Czech Republic

Petra Vasickova1, Eva Machackova1, Miroslava Lukesova1, Jiri Damborsky2, Ondrej Horky3, Hana Pavlu1, Jitka Kuklova1, Veronika Kosinova1, Marie Navratilova1 and Lenka Foretova1*

  • * Corresponding author: Lenka Foretova foretova@mou.cz

  • † Equal contributors

Author Affiliations

1 Masaryk Memorial Cancer Institute, Brno, Czech Republic

2 Loschmidt Laboratories, Faculty of Science, Masaryk University, Brno, Czech Republic

3 Center of Molecular Biology and Gene Therapy, University Hospital, Brno, Czech Republic

For all author emails, please log on.

BMC Medical Genetics 2007, 8:32  doi:10.1186/1471-2350-8-32

Published: 11 June 2007

Abstract

Background

Alterations in the highly penetrant cancer susceptibility gene BRCA1 are responsible for the majority of hereditary breast and/or ovarian cancers. However, the number of detected germline mutations has been lower than expected based upon genetic linkage data. Undetected deleterious mutations in the BRCA1 gene in some high-risk families could be due to the presence of intragenic rearrangements as deletions, duplications or insertions spanning whole exons. Standard PCR-based screening methods are mainly focused on detecting point mutations and small insertions/deletions, but large rearrangements might escape detection.

The purpose of this study was to determine the type and frequency of large genomic rearrangements in the BRCA1 gene in hereditary breast and ovarian cancer cases in the Czech Republic.

Methods

Multiplex ligation-dependent probe amplification (MLPA) was used to examine BRCA1 rearrangements in 172 unrelated patients with hereditary breast and/or ovarian cancer syndrome without finding deleterious mutation after complete screening of whole coding regions of BRCA1/2 genes. Positive MLPA results were confirmed and located by long-range PCR. The breakpoints of detected rearrangements were characterized by sequencing.

Results

Six different large deletions in the BRCA1 gene were identified in 10 out of 172 unrelated high-risk patients: exons 1A/1B and 2 deletion; partial deletion of exon 11 and exon 12; exons 18 and 19 deletion; exon 20 deletion; exons 21 and 22 deletion; and deletion of exons 5 to 14. The breakpoint junctions were localized and further characterized. Destabilization and global unfolding of the mutated BRCT domains explain the molecular and genetic defects associated with the exon 20 in-frame deletion and the exon 21 and 22 in-frame deletion, respectively.

Conclusion

Using MLPA, mutations were detected in 6% of high-risk patients previously designated as BRCA1/2 mutation-negative. The breakpoints of five out of six large deletions detected in Czech patients are novel. Screening for large genomic rearrangements in the BRCA1 gene in the Czech high-risk patients is highly supported by this study.