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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the involvement of BRCA1, which plays a major role in Western breast cancer families, in Japanese breast cancer families. Eleven families, in which at least three individuals within third degree relatives were affected by breast cancer, were collected. Five of them were early-onset breast cancer families, in which the average age at diagnosis was less than 45 years, and the other six were late-onset families. Ovarian cancer was observed in one patient in the early-onset families. Using seven polymorphic markers on chromosome 17q21, D17S250, ERBB2, THRA1, D17S579, D17S588, GIP and NME1, linkage to BRCA1 was analyzed. Linkage was not detected in any single family. Assuming homogeneity in an inherited component that confines the susceptibility to breast cancer in all families, we summed the LOD scores of all families. The cumulative LOD score obtained was -1.86 for D17S588 at theta = 0.001, indicating no linkage with BRCA1. Since the proportion of families linked to BRCA1 is larger in Western early-onset breast cancer families than in late-onset ones, we also summed the LOD scores of five early-onset families. However, again a negative LOD score was obtained. These results suggest that BRCA1 is not a major breast cancer susceptibility gene in Japanese familial breast cancer.
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PMID:Linkage analysis of BRCA1 in Japanese breast cancer families. 785 87

The breast cancer susceptibility gene BRCA1 has been cloned and a second susceptibility gene, BRCA2, chromosomally mapped; will most breast and ovarian cancer turn out to be familial?
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PMID:Familial breast cancer. BRCA1 down, BRCA2 to go. 787 85

Risks for breast cancer when there is a family history of the disease are usually calculated using data from segregation analyses which favour a single dominant gene with high penetrance. There are, however, at least three loci known to be associated with familial breast cancer (p53, BRCA1, and an as yet unpublished locus) and the frequencies and penetrances of these genes are not likely to be the same. We have attempted to address the problem of which genetic parameters should be used to calculate risks for different patterns of familial breast cancer. Data from 384 nuclear families ascertained through a proband selected for early onset breast cancer were subjected to complex segregation analysis, correcting for ascertainment bias resulting from selection for severe phenotype. Age of onset of breast cancer, incorporated as severity, provides additional information to the segregation model over and above that given by assigning liability classes on the basis of age at observation. The use of this additional parameter in the analysis is described. There is fair agreement between estimates from this sample and previous predictions from consecutive probands and consultands. The differences suggest more than one rare dominant gene for susceptibility to breast cancer, with different penetrances. Although refinements of segregation analysis will help to delineate these different genes, perfect resolution will require identification of the mutant alleles. Methods to estimate genetic parameters under genotype specific mortality need to be developed. Meanwhile, we suggest that high and low estimates of penetrance be used in risk estimation for genetic counselling, and as a guide to candidates for entry into clinical trials of screening and chemoprevention in breast cancer.
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PMID:Genetic epidemiology of early onset breast cancer. 789 76

Recent discoveries in the field of molecular-genetic research make it possible to detect an increased genetic risk of tumours, because several genes are linked to hereditary forms of breast cancer. The breast cancer gene BRCA1, located on chromosome 17q, is quantitatively the most important gene so far. A BRCA1 gene mutation is estimated to occur in 1-3 per 1000 women in the general population, i.e. in about 10,000 women among the 4 million Dutch women aged 25-55 years. In this study experiences are described concerning oncologic, clinical-genetic and psychologic aspects in the first Dutch family in which a BRCA1-gene defect was detected with the corresponding hereditary breast/ovarian cancer syndrome. Of the relatives 88% participated in the genetic family study and 76% wished to be informed on the individual DNA-test results. From the first-degree relatives of the breast cancer patients 54% appeared to be gene mutation carrier. The detection of a gene mutation in a woman could make her decide to undergo preventive mastectomy and (or) ovariectomy, besides regular breast examination and mammography. Surgeons and radiotherapists, the group of doctors who treat primary breast cancer, have to anticipate more radical operations with regard to breasts in this selected group of (future) patients. Detection of the gene may also have consequences for family planning. Identification of carriers of the gene mutation can lead to a selection of women with increased risk of breast cancer. Primary or secondary preventive measures, early diagnostic management and regular examination may lead to a decrease in death from breast cancer.
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PMID:[Initial Dutch results with a presymptomatic DNA tests in familial breast/ovarian carcinoma. Rotterdamse Werkgroep voor Erfelijke Tumoren]. 789 65

Women who carry mutations in the BRCA1 gene on chromosome 17q have an 85% lifetime risk of breast cancer, and a 60% risk of ovarian cancer. We have identified BRCA1 mutations in 12 of 30 (40%) Canadian families with breast and/or ovarian cancer, including six of the eight families (75%) that contained two cases of early-onset breast cancer and two cases of ovarian cancer. Six frameshift mutations account for all 12 mutant alleles, including nucleotide insertions (two mutations) and deletions (four mutations). Four independent families carried the same 1 basepair (bp) insertion mutation in codon 1755 and four other families shared a 2 bp deletion mutation in codons 22-23. These families were not known to be related, but haplotype analysis suggests that the carriers of each of these mutations have common ancestors.
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PMID:Common origins of BRCA1 mutations in Canadian breast and ovarian cancer families. 789 92

We provide genetic evidence supporting the identity of the candidate gene for BRCA1 through the characterization of germline mutations in 63 breast cancer patients and 10 ovarian cancer patients in ten families with cancer linked to chromosome 17q21. Nine different mutations were detected by screening BRCA1 DNA and RNA by single-strand conformation polymorphism analysis and direct sequencing. Seven mutations lead to protein truncations at sites throughout the gene. One missense mutation (which occurred independently in two families) leads to loss of a cysteine in the zinc binding domain. An intronic single basepair substitution destroys an acceptor site and activates a cryptic splice site, leading to a 59 basepair insertion and chain termination. The four families with both breast and ovarian cancer had chain termination mutations in the N-terminal half of the protein.
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PMID:Confirmation of BRCA1 by analysis of germline mutations linked to breast and ovarian cancer in ten families. 789 93

Germline mutations in a gene on chromosome 17q known as BRCA1 are responsible for a large proportion of inherited predispositions to breast and ovarian cancer. In 33 families with evidence of linkage to BRCA1, we estimated the risks of breast and ovarian cancer from the occurrence of second cancers in individuals with breast cancer, and examined the risks of other cancers in BRCA1 carriers. 26 contralateral primary breast cancers occurring more than 3 years after a first breast cancer were observed before age 70, giving an estimated cumulative risk of breast cancer in gene carriers of 87% by age 70.23 primary ovarian cancers occurred in women with a previous breast cancer, resulting in an estimated cumulative risk of ovarian cancer of 44% by age 70.87 cancers other than breast or ovarian cancer were observed in individuals with breast or ovarian cancer and their first-degree relatives compared with 69.3 expected, based on national incidence rates. Significant excesses were observed for colon cancer (estimated relative risk [RR] to gene carriers 4.11 [95% CI 2.36-7.15]) and prostate cancer (3.33 [1.78-6.20]). No significant excesses (or deficits) were noted for cancers of other sites. Our study provides estimates of breast and ovarian cancer risks which are useful for counselling BRCA1-mutation carriers. It also shows that carriers are at increased risk of colon and prostate cancer, which may be of clinical significance in certain families if the risks are associated with specific mutations.
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PMID:Risks of cancer in BRCA1-mutation carriers. Breast Cancer Linkage Consortium. 790 78

The past year has seen a great deal of excitement in the field of breast cancer genetics. Since linkage of the familial breast-ovarian cancer gene (BRCA1) to chromosome 17, the critical region has been narrowed to 1.0-1.5 Mb by recombination studies, a detailed physical map has been constructed and much of the region has been cloned in yeast artificial chromosome, bacteriophage P1 and cosmid vectors. The focus now lies on identifying the genes housed within the BRCA1 region and scanning them for oncogenic mutations.
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PMID:Towards cloning the familial breast-ovarian cancer gene on chromosome 17. 791 22

Loss of heterozygosity data from familial tumors suggest that BRCA1, a gene that confers susceptibility to ovarian and early-onset breast cancer, encodes a tumor suppressor. The BRCA1 region is also subject to allelic loss in sporadic breast and ovarian cancers, an indication that BRCA1 mutations may occur somatically in these tumors. The BRCA1 coding region was examined for mutations in primary breast and ovarian tumors that show allele loss at the BRCA1 locus. Mutations were detected in 3 of 32 breast and 1 of 12 ovarian carcinomas; all four mutations were germline alterations and occurred in early-onset cancers. These results suggest that mutation of BRCA1 may not be critical in the development of the majority of breast and ovarian cancers that arise in the absence of a mutant germline allele.
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PMID:BRCA1 mutations in primary breast and ovarian carcinomas. 793 30

We have constructed a physical map of a 4 cM region on chromosome 17q12-21 that contains the hereditary breast and ovarian cancer gene BRCA1. The map comprises a contig of 137 overlapping yeast artificial chromosomes and P1 clones, onto which we have placed 112 PCR markers. We have localized more than 20 genes on this map, ten of which had not been mapped to the region previously, and have isolated 30 cDNA clones representing partial sequences of as yet unidentified genes. Two genes that lie within a narrow region defined by meiotic breakpoints in BRCA1 patients have been sequenced in breast cancer patients without revealing any deleterious mutations. These new reagents should facilitate the identification of BRCA1.
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PMID:A physical map and candidate genes in the BRCA1 region on chromosome 17q12-21. 795 16


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