Characterization of two novel BRCA1 germ-line mutations involving splice donor sites.

Publication/Presentation Date

1-1-2004

Abstract

Deleterious BRCA1 mutations have significant clinical implications for the patients that carry them. Point mutations in critical functional domains and frameshift mutations that lead to early termination of protein translation are associated with a 60-80% risk of breast cancer and a 20-40% risk of ovarian cancer. In contrast, the significance of mutations located in intronic regions of BRCA1, even in the setting of a family history of breast and ovarian cancer, is not always clear. Some of these mutations occur in splice donor/acceptor consensus sites. These mutations can affect heteronuclear RNA (hnRNA) processing, leading to the loss of functional BRCA1 protein and thus may be disease-associated. However, it is important to verify the effect of these mutations, because splicing alterations cannot be predicted from genomic sequence alone. We report here the characterization of two novel BRCA1 mutations identified in families seen in our cancer risk evaluation clinic that alter splice donor sites of BRCA1. We show that both mutations alter transcript splicing and result in truncated BRCA1. IVS17 + 1G --> T leads to inclusion of part of intron 17 after the coding sequence of exon 17, resulting in early termination of BRCA1 protein following codon 1692. 252del5insT abolishes the splice donor site in exon 3, leading to the skipping of exon 5 and BRCA1 protein truncation following codon 45. Thus, both mutations result in loss of BRCA1 function, and carriers of these mutations should be counseled in the same manner as carriers of other truncating BRCA1 mutations.

Volume

8

Issue

2

First Page

133

Last Page

138

ISSN

1090-6576

Disciplines

Medicine and Health Sciences

PubMedID

15345110

Department(s)

Hematology-Medical Oncology Division

Document Type

Article

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