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Y J Bignon

Publications and source records attributed to Y J Bignon.

At least 73 records · Page 4Linked to original sources
PubMed1997

Detection of heterozygous carriers of the ataxia-telangiectasia (ATM) gene by G2 phase chromosomal radiosensitivity of peripheral blood lymphocytes.

In ataxia-telangiectasia (A-T) patients, mutations in a single gene, ATM, result in an autosomal recessive syndrome that embraces a variety of clinical features and manifests extreme radiosensitivity and a strong pre-disposition to malignancy. Heterozygotes for the ATM gene have no clinical expression of A-T but may be cancer prone with a moderate increase in in vitro radiosensitivity. We performed a blind chromosomal analysis on G2-phase lymphocytes from 7 unrelated A-T patients, 13 obligate A-T heterozygotes (parents of the patients), and 14 normal controls following X-irradiation with 1 Gy in order to evaluate this cytogenetic method as a tool for detection of ATM carriers. Both A-T homozygotes and heterozygotes showed significantly increased levels of radiation-induced chromatid damage relative to that of normal controls. These results show that the G2-phase chromosomal radiosensitivity assay can be used for the detection of A-T heterozygotes. In combination with molecular genetic analyses, this test may be of value in studies of familial and sporadic cancers aimed at determination of the potential involvement of ATM mutations in tumor risk or development.

Adolescent↗
PubMed1997

Loss of heterozygosity at 7q31 in breast cancer: results from an International Collaborative Study Group. The Breast Cancer Somatic Genetics Consortium.

Loss of heterozygosity (LOH) at 7q31 has been claimed to occur in over 80% of all breast cancers and to be of prognostic significance. This would make this genetic alteration the most common event observed in breast cancer to date. Others, however, have been unable to confirm this high incidence. In this multicenter study, we have complied LOH scorings for three polymorphic markers for 7q31-q32 in 683 breast tumors. Although some significant differences between centers existed, no center reported more than 40% LOH, and the average rate was 19%. Disease-free and overall survival of the patients whose tumors carried LOH at 7q31 did not differ significantly from those patients whose tumors showed retention of heterozygosity at 7q31. In a double-blind scoring of a subset of the raw data, an average discordant rate of LOH scoring of 12% was observed. While startling in itself, this was unable to explain the variation among centers, nor the difference with the initially reported high rate of LOH. We conclude that LOH at 7q31 is not important as a genetic alteration in breast cancer as originally suggested, nor a strong determinant of disease outcome.

Breast Neoplasms↗
PubMed1997

[Tracking the gatekeeper gene in the stages of carcinogenesis in the bladder].

Bladder cancers display different forms from superficial to aggressive tumours with muscle invasion. Many studies on this disease have been carried out in order to better understand the molecular mechanisms involved in its progression. Two loci are frequently associated with bladder tumorigenesis. The chromosome 9 lesions seem to be earlier involved in carcinogenesis, and suggest the presence of a tumour suppressor gene, and on the other hand the TP53 gene mutations (17q13.1) are later but take place in tumour progression. These alterations could be used as early diagnosis tool in bladder tumours and orientate the search for the bladder cancer gatekeeper gene(s).

Chromosome Mapping↗
PubMed1997

[What's new about microsatellite instability significance in human carcinogenesis?].

Microsatellite instabilities (MIN) represent a new type of mutation characterized by genomic instability (or replication error phenotype, RER+). First identified in sporadic and familial colorectal tumors, the RER+ phenotype has been sought in multiple types of cancers. Thus, two types of instability mechanisms have been shown: one due to inactivation of the mismatch repair system (phenotype RER+) and a second still unclear (instability of tri- and tetra-nucleotide repeats). In both cases, MIN seem to be the reflect of a new tumorigenesis pathway. In the context of mismatch repair defect, numerous observations show that, although instabilities seem to be random, they play a direct role in the tumoral process by altering genes that control cell growth and apoptosis. Today, MIN, as well as the detection of mutations in the DNA mismatch repair genes, can be used as diagnosis tools in oncology and provide usefull indications to adapt the chemotherapy to the disease.

Cell Division↗
PubMed1996

[Search for genetic risk in surgical indications in oncology].

We report the case of 68-year-old woman with an adenocarcinoma of the right colon. The family history also suggested that she might also be at risk of ovarian or endometrial cancer. Thus despite the lack of gynecologic symptoms, abdominal hysterectomy and bilateral salpingo-oophorectomy was proposed at the time of the right colectomy endometrial carcinoma was discovered at surgery. This finding and the family pedigree were consistent with the diagnosis of familial Lynch II syndrome. Appropriate biomolecular analyses were undertaken. This case shows the importance of family history taking in patients with cancer. The surgeon should be aware of such situations and correlate indications and procedures with the genetic risk of the patients.

Adenocarcinoma↗
PubMed1996

Cancer genetics clinics: target population and consultees' expectations.

The aim of this study was to determine in healthy consultees attending cancer genetics clinics their risk status, their pathways leading to the clinics, their expectations and perception of cancer risk. In 1994, the consultees at six French centres completed a questionnaire before their first oncogenetic consultation. The oncogeneticists subsequently filled in a standardised form giving their risk assessment. Among the 206 healthy consultees, 91.3% were women, 92.2% had at least one cancer-affected first-degree relative and 73% had a "cancer family risk" as assessed by the oncogeneticist. Sixty-nine per cent of the consultees were referred to the clinics by a physician, 10.4% by their family and 18.8% on their own initiative: 83.5% of the sample perceived their family risk of cancer as being high and this belief was confirmed in 74.3% of the cases studied by the oncogeneticist. The families of self-referred consultees were less often at risk than those of consultees referred by a physician or by their family (P = 0.012). The majority (78%) expected to be informed about cancer prevention and screening, and this expectation depended on the consultee's level of education (P = 0.001). This study shows that medical pathways are more effective than the media as a means of reaching the members of the general population who are genuinely at risk, and shows that fuller information about prevention needs to be provided at cancer genetic consultations.

Adult↗
PubMed1996

Attitudes towards cancer predictive testing and transmission of information to the family.

Before the organisation of breast cancer predictive testing in France, consultands' attitudes towards this kind of testing and towards passing on information about the family cancer risk to their relatives were investigated. This survey was carried out from January 1994 to January 1995 at six specialised cancer genetic clinics located in different parts of France Female consultands who were first degree relatives of cancer patients and who had at least one case of breast cancer in their family, affecting either themselves or a first degree relative or both, participated in this study. Among the 248 eligible consultands attending the clinics during the study period, 84.3% answered a post-consultation questionnaire. Among the 209 respondents, 40.7% (n = 85) were cancer patients and 59.3% (n = 124) were healthy consultands. A high consensus in favour of genetic testing was noted, since 87.7% of the sample stated that they would ask for breast cancer gene testing if this test became available. The underlying assumption of 96.6% of the women was that their health surveillance would be improved after a positive test. A high awareness of the anxiety that would be generated in a family after a positive result was observed and found to be associated (p < 0.05) with the anxiety and depressive profiles of the patients. Half of the healthy respondents said they would not change their attitude towards screening if the results of predictive testing turned out to be negative. Only 13.7% of the 161 patients who stated that the oncogeneticists asked them to contact their relatives firmly refused to do so, mainly because of difficult family relationships.

Adult↗
PubMed1996

[Ataxia telangiectasia and genetic predisposition to cancer].

Ataxia telangiectasia (AT) is a genetic disorder with an autosomic recessive transmission. Occurring during childhood, it affects different organs and/or systems. Physiopathology is still unclear. The first clinical signs are evident early in childhood and evolution always leads to death. The secondary cause of mortality in 10 to 15% of the affected is the development of cancers. Genetic predisposition to cancer for homozygotes, as well as for heterozygotes, is one of the most remarkable aspects of this disease. For heterozygotes the risk of cancer is three times that of the norm. The gene responsible for the disease has been cloned. Its function may resolve some questions, and provide the link between degenerative process, cancer susceptibility and immunodeficiency evident in AT patients.

Ataxia Telangiectasia↗
PubMed1996

[Hereditary predispositions to cancer: the genetic diagnosis in practice].

Genetic consultations allow to identify families in which an hereditary predisposition to cancer is transmitted. In most cases the gene involved can be studied leading to identification of families members carrying or not the mutation conferring the cancer risk. In this case, cancer risk is more accurately explained and measures, adjusted to the risk, were proposed for early screening of the disease. Capacities to characterize an inherited mutation of the susceptibility gene vary according to our knowledge of the gene, its structure, its function, the kind of mutation(s) and also, the available techniques. The purpose of this paper is to describe the most frequently used techniques for direct or indirect molecular diagnosis of cancer predisposition and to specify, for each of them, the situations where its use seem the fittest. The example of breast cancer hereditary predisposition, where multiple susceptibility genes were identified and other are still unknown, illustrates the various degree of diagnosis that can be proposed and the strategy techniques used according to the gene.

Breast Neoplasms↗
PubMed1994

Lack of germ-line mutations in the p53 gene exons 4 to 8 in patients with late-onset second malignant neoplasms.

Previous studies have shown p53 germ-line mutations in some familial cancer aggregations with or without the Li-Fraumeni syndrome (LFS). Such mutations were also reported in children and young adults with second malignant neoplasms (SMN). This led us to screen for p53 germ-line mutations in a group of seven patients affected with SMN, but characterized by an older age of onset than in the previous reports. No mutation was found in exons 4 to 8 and their boundaries using the single-strand conformation polymorphism technique. Our results give strong evidence for genetic heterogeneity of SMN, probably related to the age of cancer onset.

Adult↗
PubMed1994

[Criteria of genetic predisposition to hereditary non polyposis colorectal cancers].

Clinical and histological characteristics of non polypoid colorectal cancers with an hereditary predisposition are presented. The various known genetic syndromes (hereditary non polyposis colorectal cancers, Lynch syndrome type I and type II, Torre-Muir's syndrome, hereditary flat adenoma syndrome) are discussed to find a possible correlation between this nosological classification and their molecular substratum. The main problem today, is to correctly define the population of hereditary predisposed patients to colon cancer, in order to seek and identify the major responsible gene. Any physician, specialist or not, should be encouraged to give the details of the cancer familial context of his patients, in order to aid the oncologist geneticist in his task.

Adult↗
PubMed1994

[Genetics and cancer of the breast].

Breast carcinoma is the commonest cancer in women. Segregation analyses support the existence of a major susceptibility gene with a dominant pattern of inheritance in 4 to 10% of cases. Three genes involved in the genetic predisposition to breast tumors have recently been identified: BRCA-1 associated with early onset familial breast cancer and breast/ovarian carcinoma syndrome, p53 associated with Li-Fraumeni syndrome, and the androgen receptor gene in male breast cancer with Reinfenstein syndrome. A better understanding of inherited contribution may have important implications for screening individuals at high-risk in families.

Ataxia Telangiectasia↗
PubMed1994

Detection of allelic losses on 17q12-q21 chromosomal region in benign lesions and malignant tumors occurring in a familial context.

A predisposing gene (BRCA-1) for breast and ovarian cancer has been located on chromosomal region 17q12-21. According to Knudson's hypothesis if this gene is a tumor suppressor gene, allelic losses would be found in tumors occurring in families with cancer aggregations. We studied 25 samples of both benign lesions and malignant tumors, from breast cancer site-specific families and other familial cancer aggregations. Allelic losses seem to be more frequent in tumors from breast site-specific families but also include the predisposing locus in other syndromes, suggesting a role of BRCA-1 in such families. Finding of allele losses near this locus in benign lesions suggests that such alterations may represent a first step in breast carcinogenesis. It is noteworthy that allele losses involve larger chromosome fragments in malignant tumors than in benign lesions where BRCA-1 is not lost, suggesting a similar mechanism for genomic deletion in the tumorigenesis of the colon and of the breast.

Alleles↗