Caution should be taken in the methodology used to confirm c.156_157insAlu BRCA2 mutation

Machado, Patrícia Maria Abreu; Vaz, Fátima

doi:10.1007/s10549-008-0124-0

Cited by 3 publications

(7 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, the abnormal shorter PCR product, corresponding to the delta3-transcript, was very faint and not always detectable (Figure 2a). This observation could explain why Machado et al [11] and Peixoto et al [12] report discordant results. Fragment analysis with a fluorophore on an automatic sequencer gave reliable results, which were confirmed with PCR products spanning exons 2 to 10 (data not shown).…”

Section: Resultsmentioning

confidence: 94%

An entire exon 3 germ-line rearrangement in the BRCA2 gene: pathogenic relevance of exon 3 deletion in breast cancer predisposition

Muller¹,

Rouleau

Schultz³

et al. 2011

BMC Med Genet

View full text Add to dashboard Cite

BackgroundGerm-line mutations in the BRCA1 and BRCA2 genes are major contributors to hereditary breast/ovarian cancer. Large rearrangements are less frequent in the BRCA2 gene than in BRCA1. We report, here, the first total deletion of exon 3 in the BRCA2 gene that was detected during screening of 2058 index cases from breast/ovarian cancer families for BRCA2 large rearrangements. Deletion of exon 3, which is in phase, does not alter the reading frame. Low levels of alternative transcripts lacking exon 3 (Δ3 delta3 transcript) have been reported in normal tissues, which raises the question whether deletion of exon 3 is pathogenic.MethodsLarge BRCA2 rearrangements were analysed by QMPSF (Quantitative Multiplex PCR of Short Fluorescent Fragments) or MLPA (Multiplex Ligation-Dependent Probe Amplification). The exon 3 deletion was characterized with a "zoom-in" dedicated CGH array to the BRCA2 gene and sequencing. To determine the effect of exon 3 deletion and assess its pathogenic effect, three methods of transcript quantification were used: fragment analysis of FAM-labelled PCR products, specific allelic expression using an intron 2 polymorphism and competitive quantitative RT-PCR.ResultsLarge rearrangements of BRCA2 were detected in six index cases out of 2058 tested (3% of all deleterious BRCA2 mutations). This study reports the first large rearrangement of the BRCA2 gene that includes all of exon 3 and leads to an in frame deletion of exon 3 at the transcriptional level. Thirty five variants in exon 3 and junction regions of BRCA2 are also reported, that contribute to the interpretation of the pathogenicity of the deletion. The quantitative approaches showed that there are three classes of delta3 BRCA2 transcripts (low, moderate and exclusive). Exclusive expression of the delta3 transcript by the mutant allele and segregation data provide evidence for a causal effect of the exon 3 deletion.ConclusionThis paper highlights that large rearrangements and total deletion of exon 3 in the BRCA2 gene could contribute to hereditary breast and/or ovarian cancer. In addition, our findings suggest that, to interpret the pathogenic effect of any variants of exon 3, both accurate transcript quantification and co-segregation analysis are required.

show abstract

Section: Resultsmentioning

confidence: 94%

An entire exon 3 germ-line rearrangement in the BRCA2 gene: pathogenic relevance of exon 3 deletion in breast cancer predisposition

Muller¹,

Rouleau

Schultz³

et al. 2011

BMC Med Genet

View full text Add to dashboard Cite

show abstract

“…We wish to reply to the Letter to the Editor written by Machado and Vaz [1] concerning our recently published article on the c.156_157insAlu BRCA2 founder mutation [2], first discovered by Teugels et al [3] in a Portuguese patient living in Belgium. That letter has several misstatements about our and others' work that must not remain unchallenged.…”

mentioning

confidence: 97%

“…Machado and Vaz suggest in their letter [1] that we diagnose the c.156_157insAlu BRCA2 mutation by subjective evaluation of band intensities after RT-PCR. We think that it is clear in our paper [2], under the subheading ''Screening for the c.156_157insAlu BRCA2 mutation'', that we screen for this mutation by using two independent PCRs, one for exon 3 amplification and another specific for the Alu rearrangement.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Molecular diagnosis of the Portuguese founder mutation BRCA2 c.156_157insAlu

Peixoto¹,

Santos²,

Rocha³

et al. 2008

Breast Cancer Res Treat

View full text Add to dashboard Cite

“…All authors agree that this highly recurrent mutation initially occurred in a single patient (founder effect), but with some disagreement about which method to use for the molecular identification of the high breast cancer risk mutation carriers. In a letter to the editor of this journal, Machado and Vaz proposed a three step PCR assay for which they have a patent pending [4]. The mutant BRCA2 allele is unable to generate wild type full length mRNA, but a shorter messenger missing exon 3 (the target exon for the Alu repeat insertion).…”

mentioning

confidence: 99%