Molecular analysis of the BRCA1 and BRCA2 genes in 32 breast and/or ovarian cancer Spanish families.
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It is estimated that about 5-10% of breast cancer cases may be due to inherited predisposition. Until now, two main susceptibility genes have been identified: BRCA1 and BRCA2. The first linkage and mutational studies suggested that mutations in these two genes would account for the majority of high-risk breast cancer families, but recent studies show how the proportion of families due to BRCA1 or BRCA2 mutations strongly depends on the population and the types of family analyzed. It is now clear that, in the context of families with a modest cancer profile, which are the most commonly found in the clinical practice, the percentage of mutations found is much lower than that suggested by the first studies. In the present study, we analyze a group of 32 Spanish families, which contained at least three cases of female breast cancer (at least one of them diagnosed before the age of 50 years), for the presence of mutations in the BRCA genes. The total proportion of mutations was low (25%), although the percentage of mutations in the BRCA1 and BRCA2 genes was higher, considering the breast and ovarian cancer families and the male breast cancer families respectively. Our results are in agreement with the idea that a great proportion of moderate-risk cancer families could be due to low penetrance susceptibility genes distinct from BRCA1 or BRCA2. (+info)
Testing for hereditary breast and ovarian cancer in the southeastern United States.
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OBJECTIVES: To detail characterization of mutations and uncharacterized variants in the breast cancer susceptibility genes BRCA1 and BRCA2, as observed in a population of breast cancer patients from the southeastern United States, and to examine baseline characteristics of women referred for counseling and testing and provide a preliminary look at how counseling and testing affected intentions toward prophylactic surgery. BACKGROUND: Mutations in the BRCA1 and BRCA2 genes give rise to a dramatically increased risk of developing breast or ovarian cancer or both. There are many reports about special populations in which deleterious mutations are present at a high frequency. It is useful to study these genes in more heterogeneous populations, reflecting different geographic regions. Interest in preventive surgery for gene carriers is high in women and their surgeons. METHODS: Women were recruited through a prospective clinical trial of counseling and free genetic testing. BRCA1 and BRCA2 were screened for mutations using standard techniques, and results were given to participants. Baseline questionnaires determined interest in preventive surgery at the beginning of the study. Follow-up questionnaires for those who completed testing surveyed interest in prophylactic surgery after counseling and receiving test results. RESULTS: Of 213 women who completed counseling and testing, 44 (20.6%) had 29 separate mutations; there were 11 Jewish women carrying three founder mutations. Twenty-eight women (13.1%) had uncharacterized variants in BRCA1 or BRCA2; nine were not previously reported. Women overestimated their chances of possessing a deleterious gene mutation compared to a statistical estimate of carrier risk. A number of women changed their intentions toward preventive surgery after genetic counseling and testing. CONCLUSIONS: Hereditary breast cancer due to mutations in BRCA1 and BRCA2 was a heterogeneous syndrome in the southeastern United States. Most mutations were seen just once, and uncharacterized variants were common and of uncertain clinical significance. In general, positive test results tended to reinforce intentions toward prophylactic surgery. In contrast, women not interested in surgery at the time of entry tended to remain reluctant after testing and counseling. (+info)
Atypical medullary carcinoma of the breast with cartilaginous metaplasia in a patient with a BRCA1 germline mutation.
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We examined a 34-year-old premenopausal woman who had noticed a left-breast lump a month previously. She had no past history of malignancies but had a family history of breast and ovarian cancers. Her mother had suffered from ovarian cancer when aged 47 years and had died of the disease at age 52. The younger two of the patient's four aunts had developed breast cancer when they were 37 and 48 years old. A physical examination showed an ill-defined mass, 1.5 cm in diameter, located in the upper outer quadrant of the patient's left breast. Mammography revealed diffuse microcalcification in both breasts but ultrasonography revealed an irregular tumorous lesion only in the left breast. Aspiration breast cytology revealed adenocarcinoma of the left breast. Modified radical mastectomy of the left breast and excision of a biopsy specimen from the right breast were carried out simultaneously. Histopathologically the left-breast tumor was an atypical medullary carcinoma with cartilaginous metaplasia, of histological grade 3, and the right-breast specimen showed fibrocystic changes with atypical ductal hyperplasia. Estrogen receptors were positive, but progesterone receptor was not detected on the tumor cells, which were immunopositive for nuclear p53 although c-erbB-2 overexpression was not observed. A nonsense germline mutation of the BRCA1 gene (exon5) was detected. The patient has been well since the operation (10 months). These findings may provide useful information about the carcinogenesis and biological behavior of BRCA1-associated breast cancers. (+info)
Laminin-rich extracellular matrix association with mammary epithelial cells suppresses Brca1 expression.
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Brca1 mRNA was detectable in female mouse mammary gland tissue from adult virgins, during pregnancy and early lactation. It was associated with phases of mammary epithelial cell proliferation and differentiation but the pattern of Brca1 expression was dissociable from that of a true differentiation marker, beta-casein, by virtue of its significant expression in the virgin gland and termination of its expression in early lactation. In a primary cell culture model, association of a laminin-rich extracellular matrix (ECM) with mammary epithelial cells was required for cell survival and cell differentiation and suppressed Brca1 expression in these cells. ECM-association may significantly contribute to the final restriction in Brca1 expression in the lactating gland in vivo. Interestingly, our results suggest that mammary epithelial cells undergo apoptosis both when expressing and when not expressing Brca1, depending on whether the dying cell populations had been terminally differentiated or not. (+info)
Founder mutations in the BRCA1 gene in Polish families with breast-ovarian cancer.
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We have undertaken a hospital-based study, to identify possible BRCA1 and BRCA2 founder mutations in the Polish population. The study group consisted of 66 Polish families with cancer who have at least three related females affected with breast or ovarian cancer and who had cancer diagnosed, in at least one of the three affected females, at age <50 years. A total of 26 families had both breast and ovarian cancers, 4 families had ovarian cancers only, and 36 families had breast cancers only. Genomic DNA was prepared from the peripheral blood leukocytes of at least one affected woman from each family. The entire coding region of BRCA1 and BRCA2 was screened for the presence of germline mutations, by use of SSCP followed by direct sequencing of observed variants. Mutations were found in 35 (53%) of the 66 families studied. All but one of the mutations were detected within the BRCA1 gene. BRCA1 abnormalities were identified in all four families with ovarian cancer only, in 67% of 27 families with both breast and ovarian cancer, and in 34% of 35 families with breast cancer only. The single family with a BRCA2 mutation had the breast-ovarian cancer syndrome. Seven distinct mutations were identified; five of these occurred in two or more families. In total, recurrent mutations were found in 33 (94%) of the 35 families with detected mutations. Three BRCA1 abnormalities-5382insC, C61G, and 4153delA-accounted for 51%, 20%, and 11% of the identified mutations, respectively. (+info)
Collaboration of signal transducer and activator of transcription 1 (STAT1) and BRCA1 in differential regulation of IFN-gamma target genes.
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Most of the activities of IFN-gamma are the result of STAT1-mediated transcriptional responses. In this study, we show that the BRCA1 tumor suppressor acts in concert with STAT1 to differentially activate transcription of a subset of IFN-gamma target genes and mediates growth inhibition by this cytokine. After IFN-gamma treatment, induction of the cyclin-dependent kinase inhibitor, p21WAF1, was synergistically activated by BRCA1, whereas the IRF-1 gene was unaffected. Importantly, the differential induction of p21WAF1 was impaired in breast cancer cells homozygous for the mutant BRCA1 5382C allele. Biochemical analysis illustrated that the mechanism of this transcriptional synergy involves interaction between BRCA1 aa 502-802 and the C-terminal transcriptional activation domain of STAT1 including Ser-727 whose phosphorylation is crucial for transcriptional activation. Significantly, STAT1 proteins mutated at Ser-727 bind poorly to BRCA1, reinforcing the importance of Ser-727 in the recruitment of transcriptional coactivators by STAT proteins. These findings reveal a novel mechanism for BRCA1 function in the IFN-gamma-dependent tumor surveillance system. (+info)
Communicating genetic risk: pros, cons, and counsel.
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Shortly before his death in 1995, Kenneth B. Schwartz, a cancer patient at Massachusetts General Hospital (MGH), founded The Kenneth B. Schwartz Center at MGH. The Schwartz Center is a non-profit organization dedicated to supporting and advancing compassionate health care delivery, which provides hope to the patient, support to caregivers, and encourages the healing process. The center sponsors the Schwartz Center Rounds, a monthly multidisciplinary forum where caregivers reflect on important psychosocial issues faced by patients, their families, and their caregivers, and gain insight and support from fellow staff members. This case is of a woman with a personal, and a strong family history of breast cancer, who considered genetic testing for mutations in the BRCA1 and BRCA2 genes. The details of the case have been altered to protect the patient's anonymity. The patient was very anxious and there was disagreement between her healthcare providers about the potential benefits of genetic testing. The discussion of the case focused on several controversial issues, particularly the ownership of genetic information, and who is responsible for disseminating information to the family members at risk. The difficulties in communicating risk, providing emotional support and coping with the continuing uncertainties about screening and intervention are reviewed with an overview of the molecular biology, inheritance, and epidemiology of the BRCA1 and BRCA2 genes. (+info)
Mutation analysis of BRCA1 gene in African-American patients with breast cancer.
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An estimated 7% of all breast cancers and 10% of all ovarian cancers are associated with inherited mutations in BRCA1 and BRCA2 genes. The mutations of a breast cancer-susceptible gene, BRCA1, confers increased risk of breast cancer in young women. Numerous studies have reported specific mutations in the BRCA1 and BRCA2 genes in the white population. However, there are very few studies on African-American and other ethnic minority groups. The goal of this study is to identify whether African-American patients with breast cancer carry some common mutations reported in other ethnic groups and whether they carry some novel mutations. We screened hot-region mutations on exons 2, 5, 11, 16, and 20 of BRCA1 gene in 54 African-American patients with breast cancer by NIRCA and SSCP methods. Our data revealed one novel frameshift mutation (3331 insG) and three missense sequence variants (A3537G, A3667G, and C4009T) on exon 11. Each sequence change was confirmed by automatic DNA sequencing. One rare sequence variant, A3537G, has been revealed in high frequency (3/54). Our data suggested that African-American patients with breast cancer carry some unique BRCA1 gene mutations. (+info)