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Brigitte Bressac-de Paillerets

Publications and source records attributed to Brigitte Bressac-de Paillerets.

10 recordsLinked to original sources
PubMed2003

Localization of a novel melanoma susceptibility locus to 1p22.

Over the past 20 years, the incidence of cutaneous malignant melanoma (CMM) has increased dramatically worldwide. A positive family history of the disease is among the most established risk factors for CMM; it is estimated that 10% of CMM cases result from an inherited predisposition. Although mutations in two genes, CDKN2A and CDK4, have been shown to confer an increased risk of CMM, they account for only 20%-25% of families with multiple cases of CMM. Therefore, to localize additional loci involved in melanoma susceptibility, we have performed a genomewide scan for linkage in 49 Australian pedigrees containing at least three CMM cases, in which CDKN2A and CDK4 involvement has been excluded. The highest two-point parametric LOD score (1.82; recombination fraction [theta] 0.2) was obtained at D1S2726, which maps to the short arm of chromosome 1 (1p22). A parametric LOD score of 4.65 (theta=0) and a nonparametric LOD score of 4.19 were found at D1S2779 in nine families selected for early age at onset. Additional typing yielded seven adjacent markers with LOD scores >3 in this subset, with the highest parametric LOD score, 4.95 (theta=0) (nonparametric LOD score 5.37), at D1S2776. Analysis of 33 additional multiplex families with CMM from several continents provided further evidence for linkage to the 1p22 region, again strongest in families with the earliest mean age at diagnosis. A nonparametric ordered sequential analysis was used, based on the average age at diagnosis in each family. The highest LOD score, 6.43, was obtained at D1S2779 and occurred when the 15 families with the earliest ages at onset were included. These data provide significant evidence of a novel susceptibility gene for CMM located within chromosome band 1p22.

Adolescent↗
PubMed2003

BRAF as a melanoma susceptibility candidate gene?

A high frequency of activating BRAF somatic mutations have been identified recently in malignant melanoma and nevi indicating that BRAF activation could be an early and critical step in the initiation of melanocytic neoplasia. To determine whether BRAF mutations could be an earlier event occurring at the germline level, we screened the entire BRAF coding region for germline mutations in 80 independent melanoma-prone families or patients with multiple primary melanoma without a familial history. We identified 13 BRAF variants, 4 of which were silent mutations in coding regions and 9 nucleotide substitutions in introns. None of these BRAF variants segregated with melanoma in the 11 melanoma families studied. Moreover, there was no significant difference in the frequency of heterozygotes for BRAF variants between melanoma cases and controls when they were compared. Our data suggest that BRAF is unlikely to be a melanoma susceptibility gene.

Chromosome Segregation↗
PubMed2003

Screening for TP53 rearrangements in families with the Li-Fraumeni syndrome reveals a complete deletion of the TP53 gene.

The absence of detectable germline TP53 mutations in a fraction of families with Li-Fraumeni syndrome (LFS) has suggested the involvement of other genes, but this hypothesis remains controversial. The density of Alu repeats within the TP53 gene led us to search genomic rearrangements of TP53 in families without detectable TP53 mutation. To this aim, we adapted the quantitative multiplex PCR of short fluorescent fragments (QMPSF) method to the analysis of the 11 exons of TP53. We analysed 98 families, either fulfilling (six families) or partially meeting (92 families) the criteria for LFS, and in which classical methods had failed to reveal TP53 alterations. We identified, in a large family fulfilling the criteria for LFS, a complete heterozygous deletion of TP53. Additional QMPSF analyses indicated that this deletion, which partially removed the centromeric FLJ10385 locus, covered approximately 45 kb. This deletion was shown to result from a complex rearrangement involving two distinct Alu-mediated recombinations. We conclude that TP53 germline rearrangements occur as rare events, but must be considered in LFS families without detectable point TP53 mutation.

DNA Primers↗
PubMed2003

eMelanoBase: an online locus-specific variant database for familial melanoma.

A proportion of melanoma-prone individuals in both familial and non-familial contexts has been shown to carry inactivating mutations in either CDKN2A or, rarely, CDK4. CDKN2A is a complex locus that encodes two unrelated proteins from alternately spliced transcripts that are read in different frames. The alpha transcript (exons 1alpha, 2, and 3) produces the p16INK4A cyclin-dependent kinase inhibitor, while the beta transcript (exons 1beta and 2) is translated as p14ARF, a stabilizing factor of p53 levels through binding to MDM2. Mutations in exon 2 can impair both polypeptides and insertions and deletions in exons 1alpha, 1beta, and 2, which can theoretically generate p16INK4A-p14ARF fusion proteins. No online database currently takes into account all the consequences of these genotypes, a situation compounded by some problematic previous annotations of CDKN2A-related sequences and descriptions of their mutations. As an initiative of the international Melanoma Genetics Consortium, we have therefore established a database of germline variants observed in all loci implicated in familial melanoma susceptibility. Such a comprehensive, publicly accessible database is an essential foundation for research on melanoma susceptibility and its clinical application. Our database serves two types of data as defined by HUGO. The core dataset includes the nucleotide variants on the genomic and transcript levels, amino acid variants, and citation. The ancillary dataset includes keyword description of events at the transcription and translation levels and epidemiological data. The application that handles users' queries was designed in the model-view-controller architecture and was implemented in Java. The object-relational database schema was deduced using functional dependency analysis. We hereby present our first functional prototype of eMelanoBase. The service is accessible via the URL www.wmi.usyd.edu.au:8080/melanoma.html.

Computer Security↗
PubMed2003

Impact of gene patents on the cost-effective delivery of care: the case of BRCA1 genetic testing.

BACKGROUND: In 1994/95, two genes, BRCA1/2, associated with a predisposition to breast or ovarian cancer were identified. Genetic testing of deleterious BRCA1/2 mutations consequently can be proposed to individuals with a family history of breast or ovarian cancer to identify who is at risk. The granting of U.S. patents on BRCA1/2 to a privately owned company has led to the monopoly use of a unique technique (Direct Sequencing of the gene, DS) for BRCA1/2 testing in this country. Alternative strategies using prescreening techniques, however, have been experienced worldwide. METHODS: On the basis of data collected at three laboratories of French public hospitals, we carried out a cost-effectiveness study comparing DS to 19 alternative strategies with the number of deleterious BRCA1 mutations detected as the outcome. RESULTS: Results show that the DS strategy presents the highest average cost per mutation detected (9,882.5 Euro) and that there exist strategies using prescreening techniques that can reach similar effectiveness while reducing total costs. Moreover, other strategies can obtain a four- to sevenfold reduction in the average cost per mutation detected as soon as some rates of false negatives (2% to 13%) are deemed to be acceptable. CONCLUSIONS: Results suggest that gene patents with a very broad scope, covering all potential medical applications, may prevent health care systems from identifying and adopting the most efficient genetic testing strategies due to the monopoly granted for the exploitation of the gene. Policy implications for regulatory authorities, in the current context of the extension of BRCA1/2 patents in other countries, are discussed.

Breast Neoplasms↗
PubMed2003

A single Mediterranean, possibly Jewish, origin for the Val59Gly CDKN2A mutation in four melanoma-prone families.

We have screened for CDKN2A germline mutations in 49 Jewish families with two or more cases of melanoma. The Val59Gly mutation, one of the three different alterations identified among these families, was also detected independently in two kindreds from France and one from Spain. The impact of the Val59Gly substitution on the function of the cyclin-dependent kinase inhibitor p16(INK4a), a product of the CDKN2A gene, was assessed by protein-protein interaction and cell proliferation assays and related to potential structural alterations predicted by molecular modeling. Seven microsatellite markers in the vicinity of the CDKN2A gene were used to determine whether the mutation in these families is identical by descent, or represents a mutational hotspot in the CDKN2A gene. Our results show that the Val59Gly substitution impairs p16(INK4a) function, and this dysfunction is consistent with structural predictions. All melanoma-affected individuals tested in the families under study harbor this mutation. Interestingly, the Israeli pedigree includes an affected individual who is homozygous for the Val59Gly mutation. A common haplotype of microsatellite markers has been demonstrated for mutation carriers in all four pedigrees. The Israeli pedigree and one of the French melanoma families are of Moroccan and Tunisian Jewish descent, respectively, and the other families originate from regions of France and Spain close to the Pyrenees. We conclude that the Val59Gly mutation is a major contributor to melanoma risk in the families under study and that it may derive from a single ancestral founder of Mediterranean (possibly Jewish) origin.

Chromosome Mapping↗
PubMed2002

Geographical variation in the penetrance of CDKN2A mutations for melanoma.

BACKGROUND: Germline mutations in the CDKN2A gene, which encodes two proteins (p16INK4A and p14ARF), are the most common cause of inherited susceptibility to melanoma. We examined the penetrance of such mutations using data from eight groups from Europe, Australia and the United States that are part of The Melanoma Genetics Consortium. METHODS: We analyzed 80 families with documented CDKN2A mutations and multiple cases of cutaneous melanoma. We modeled penetrance for melanoma using a logistic regression model incorporating survival analysis. Hypothesis testing was based on likelihood ratio tests. Covariates included gender, alterations in p14ARF protein, and population melanoma incidence rates. All statistical tests were two-sided. RESULTS: The 80 analyzed families contained 402 melanoma patients, 320 of whom were tested for mutations and 291 were mutation carriers. We also tested 713 unaffected family members for mutations and 194 were carriers. Overall, CDKN2A mutation penetrance was estimated to be 0.30 (95% confidence interval (CI) = 0.12 to 0.62) by age 50 years and 0.67 (95% CI = 0.31 to 0.96) by age 80 years. Penetrance was not statistically significantly modified by gender or by whether the CDKN2A mutation altered p14ARF protein. However, there was a statistically significant effect of residing in a location with a high population incidence rate of melanoma (P =.003). By age 50 years CDKN2A mutation penetrance reached 0.13 in Europe, 0.50 in the United States, and 0.32 in Australia; by age 80 years it was 0.58 in Europe, 0.76 in the United States, and 0.91 in Australia. CONCLUSIONS: This study, which gives the most informed estimates of CDKN2A mutation penetrance available, indicates that the penetrance varies with melanoma population incidence rates. Thus, the same factors that affect population incidence of melanoma may also mediate CDKN2A penetrance.

Australia↗
PubMed2002

Hereditary breast cancer associated with a germline BRCA2 mutation in identical female twins with similar disease expression.

The relative contribution of heritable and nonheritable factors to disease expression in BRCA2 mutation carriers is largely unknown. This report describes a familial breast cancer syndrome in a pair of identical female twins. These twins showed an extremely high concordance in their clinical histories; both twins exhibited similar cancer-related risk factors, and developed breast cancer at the same age with the same disease stage and identical histological features. No differences were detected in hormone receptors status, p53, bcl-2, erbB-2 and LI Ki67 expression by immunohistochemistry. A BRCA2 exon 11 protein truncation test showed a lower molecular weight band than the one expected for a normal allele, in both twins. Sequence analysis of DNA showed a 6 bp insertion between nucleotides 4359-4360, which resulted in a premature stop codon at position 1378. The remarkable disease similarity observed in this identical twin pair is in accordance with an important role for heritable factors in disease expression among patients carrying BRCA germline mutations.

Adult↗
PubMed2002

Testing for BRCA1 mutations: a cost-effectiveness analysis.

Breast carcinoma is the most common type of cancer affecting women in the Western world. The hereditary forms, which amount from 5 to 10% of all the cases of breast cancer, mainly involve BRCA1 or BRCA2 mutations. Due to the diagnostic strategy used by the patent owner, Direct DNA sequencing (DS) may become the only BRCA1/2 test procedure available, although there exist several alternative strategies. A cost-effectiveness study was carried out using BRCA1 testing as a model. The main techniques available for performing mutation searches were assessed: DS, denaturing high performance liquid chromatography (DHPLC), single-strand conformation polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE), heteroduplex analysis (HA), fluorescent assisted mismatch analysis (FAMA) and the protein truncation test (PTT). Twenty strategies involving the use of one or more techniques were then devised for performing the complete genetic analysis. DS was adopted as the 'gold standard' for effectiveness. All the strategies except for DS involved a two-step procedure. The first step consisted of pre-screening the 22 coding exons of BRCA1. The second step consisted of performing DS only on the variations detected in the coding sequence. The cost of the strategies tested, including a pre-screening stage, turned out to be 30 to 90% lower than that of DS, whatever annual use was made of the equipment. The most cost-effective strategy, ie, that corresponding to the lowest cost per mutation detected, was found to be a combination between PTT on exon 11 (60% of the coding sequence) and HA on the remaining 21 exons (PTT(11)+ HA(21)). However, since a high false negative rate is associated with this strategy, at least four other strategies are worth mentioning: PTT(11)+ DHPLC(21), DHPLC alone, FAMA(11)+ DHPLC(21) and FAMA alone. Our results on genetic testing for breast cancer show that DS is not the most cost-effective method available. The monopolist approach of the firm which owns the patents on the BRCA1/2 genes, may, therefore limit the use of the most cost-effective strategies.

Cost-Benefit Analysis↗