University of Oulu

The role of BACH1, BARD1 and TOPBP1 genes in familial breast cancer

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Author: Karppinen, Sanna-Maria
Organizations: University of Oulu, Faculty of Medicine, Institute of Clinical Medicine, Department of Clinical Genetics
University of Oulu, Biocenter Oulu
Format: eBook
Online Access: PDF Full Text (PDF, 1.1 MB)
Persistent link: http://urn.fi/urn:isbn:9789514291593
Language: English
Published: 2009
Publish Date: 2009-06-16
Thesis type: Doctoral Dissertation
Defence Note: Academic dissertation to be presented with the assent of the Faculty of Medicine of the University of Oulu for public defence in Auditorium 5 of Oulu University Hospital, on 26 June 2009, at 12 noon
Reviewer: Docent Outi Monni
Docent Minna Tanner
Description:

Abstract

Approximately 5–10% of all breast cancer cases are estimated to result from a hereditary predisposition to the disease. Currently no more than 25–30% of these familial cases can be explained by mutations in the known susceptibility genes, BRCA1 and BRCA2 being the major ones. Additional predisposing genes are therefore likely to be discovered. This study evaluates whether germline alterations in three BRCA1-associated genes, BACH1 (i.e. BRIP1/FANCJ), BARD1 and TOPBP1, contribute to familial breast cancer.

Altogether 214 Finnish patients having breast and/or ovarian cancer were analysed for germline mutations in the BACH1 gene. Nine alterations were observed, four of which located in the protein-encoding region. The previously unidentified Pro1034Leu was considered a possible cancer-associated alteration as it appeared with two-fold higher frequency among cancer cases compared to controls. All the other observed alterations were classified as harmless polymorphisms.

Mutation analysis of the BARD1 gene among 126 Finnish patients having family history of breast and/or ovarian cancer revealed seven alterations in the protein-encoding region. The Cys557Ser alteration was seen at an elevated frequency among familial cancer cases compared to controls (p = 0.005, odds ratio [OR] 4.2, 95% confidence interval [CI] 1.7–10.7). The other alterations appeared to be harmless polymorphisms. To evaluate further the possible effect of Cys557Ser on cancer risk, a large case-control study was performed, consisting of 3,956 cancer patients from the Nordic countries. The highest prevalence of Cys557Ser was found among breast and ovarian cancer patients from BRCA1/BRCA2 mutation-negative families (p < 0.001, OR 2.6, 95% CI 1.7–4.0). In contrast, no significant association with male breast cancer, ovarian, colorectal or prostate cancer was observed.

The current study is the first evaluating the role of TOPBP1 mutations in familial cancer predisposition. The analysis of 125 Finnish patients having breast and/or ovarian cancer revealed one putative pathogenic alteration. The commonly occurring Arg309Cys allele was observed at a significantly higher frequency among familial cancer cases compared to controls (p = 0.002, OR 2.4, 95% CI 1.3–4.2). The other 18 alterations observed were classified as harmless polymorphisms.


Series: Acta Universitatis Ouluensis. D, Medica
ISSN-E: 1796-2234
ISBN: 978-951-42-9159-3
ISBN Print: 978-951-42-9158-6
Issue: 1019
Subjects:
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