Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study.

Nearly one-half of BRCA1 and BRCA2 sequence variations are variants of uncertain significance (VUSs) and are candidates for splice alterations for example, by disrupting/creating splice sites. As out-of-frame splicing defects lead to a marked reduction of the level of the mutant mRNA cleared through nonsense-mediated mRNA decay, a cDNA-based test was developed to show the resulting allelic imbalance (AI). Fifty-four VUSs identified in 53 hereditary breast/ovarian cancer (HBOC) patients without BRCA1/2 mutation were included in the study.

Evaluation of in silico splice tools for decision-making in molecular diagnosis.

It appears that all types of genomic nucleotide variations can be deleterious by affecting normal pre-mRNA splicing via disruption/creation of splice site consensus sequences. As it is neither pertinent nor realistic to perform functional testing for all of these variants, it is important to identify those that could lead to a splice defect in order to restrict transcript analyses to the most appropriate cases. Web-based tools designed to provide such predictions are available.

A deep intronic mutation in the RB1 gene leads to intronic sequence exonisation.

Familial forms of retinoblastoma, an embryonic neoplasm of retinal origin, are caused by constitutional mutations of the RB1 gene. In this paper, we describe a family with retinoblastoma affecting two brothers with no previous family history of cancer. Complete RB1 mutational screening including point mutation and large rearrangement screening failed to demonstrate any mutation.

A high-throughput mutation detection method based on heteroduplex analysis using graft copolymer matrixes: application to Brca1 and Brca2 analysis.

We present here a new approach to electrophoretic heteroduplex analysis (EHDA) based on improved matrixes. EHDA is an appealing technique for the detection of unknown point mutations because of its simplicity and high throughput. We present here a new matrix for electrophoretic heteroduplex analysis much more sensitive for insertions, deletions, and substitutions than reported for previous EHDA separations and also superior to DHPLC.

Characterisation of a 161 kb deletion extending from the NBR1 to the BRCA1 genes in a French breast-ovarian cancer family.

A large germline deletion removing exons 1 to 22 of the BRCA1 gene has been previously detected using quantitative PCR based methods (QMPSF and real time PCR gene dosage assay) in a woman affected with breast and ovarian cancer. Here, we report its characterisation by using colour bar code on combed DNA of the BRCA1 region. The 5' boundary is located in a Alu Y sequence in NBR1 intron 18 whereas the 3' boundary is located in a Alu Sc sequence in BRCA1 intron 22.

Fidelity of DNA double-strand break repair in heterozygous cell lines harbouring BRCA1 missense mutations.

Germ-line mutations of the BRCA1 and BRCA2 genes, when they lead to a truncated protein, confer a high risk of breast and ovarian cancer. However, the role of BRCA1 missense mutations in cancer predisposition is unclear. Functional assays may be very helpful to more clearly define the biological effect of these mutations, and could therefore be useful in clinical practice.

Significant contribution of large BRCA1 gene rearrangements in 120 French breast and ovarian cancer families.

Genetic linkage data have shown that alterations of the BRCA1 gene are responsible for the majority of hereditary breast-ovarian cancers. However, BRCA1 germline mutations are found much less frequently than expected, especially as standard PCR-based mutation detection approaches focus on point and small gene alterations. In order to estimate the contribution of large gene rearrangements to the BRCA1 mutation spectrum, we have extensively analysed a series of 120 French breast-ovarian cancer cases.