[Show abstract][Hide abstract] ABSTRACT: The penetrance of the BRCA2 gene on chromosome 13q12-13 has been estimated in two large, systematically ascertained, linked families, by use of a maximum-likelihood method to incorporate both cancer-incidence data and 13q marker typings in the families. The cumulative risk of breast cancer in female gene carriers was estimated to be 59.8% by age 50 years (95% confidence interval [95% CI] 25.9%-78.5%) and 79.5% by age 70 years (95% CI 28.9%-97.5%). The cumulative risk of breast cancer in male carriers was estimated to be 6.3% (95% CI 1.4%-25.6%) by age 70 years. There was no evidence of any risk difference between the two families. These results indicate that the lifetime breast cancer risk in BRCA2 carriers, for at least a subset of mutations, is comparable to that for BRCA1. A significant excess of ovarian cancer in gene carriers was observed (relative risk 17.69, based on three cases), but the absolute risk of ovarian cancer was less than that reported for BRCA1. Significant excesses of laryngeal cancer (relative risk 7.67, based on two possible carriers) and prostate cancer (relative risk 2.89, based on five possible carriers) were also observed. One case of ocular melanoma, as well as a second eye cancer of unspecified histology, occurred in obligate gene carriers.
The American Journal of Human Genetics 08/1997; 61(1):120-8. · 11.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Interest in the genetics of breast cancer has intensified with the discovery of a breast cancer susceptibility locus, BRCA1, on chromosome 17q. In this paper, we describe updated information on a large breast cancer kindred (K107) that has been extensively studied since 1948. Specifically, we have identified many new cases of cancer in the family and have shown that this family is unlinked to BRCA1 as well as a number of other genes considered as candidates for breast cancer. In a collaborative study between the University of Utah and the Institute of Cancer Research in the United Kingdom, we have collected a set of families with a predisposition to breast and ovarian cancers that have been reliably excluded from linkage to BRCA1 and evaluated their usage in a genomic search for other breast cancer loci. This effort led to the discovery of a second breast cancer locus located on chromosome 13q, BRCA2, which is responsible for the increased incidence of breast cancer in Kindred 107.
[Show abstract][Hide abstract] ABSTRACT: Mutation of a specific, but as yet unidentified, gene BRCA1 on chromosome 17q results in increased susceptibility to breast and ovarian cancer. It is important to know the effects of this gene in terms of the age-specific risks of these cancers and the potential interaction of this gene with other known risk factors.
We performed detailed studies on a large multigenerational family, in which there is known 17q-linked breast and ovarian cancer, in order to characterize the effects of the BRCA1 mutation on development of breast and ovarian cancer.
Data from the Utah Population Database were used to identify a family (identified as K2082) with a cluster of premenopausal breast cancer and ovarian cancer at any age. Blood samples from 195 members of the family were obtained and these individuals were genotyped for a series of four chromosome 17q polymorphic markers. Information on reproductive history, cancer incidence and treatment, and lifestyle factors was collected on 72 women in the family by questionnaire or through contact with living relatives.
Odds in favor of linkage of breast and ovarian cancer in this family to the BRCA1 region of chromosome 17q are greater than 10(8) to 1. The estimated risks for breast or ovarian cancer because of the BRCA1 mutation in this family are 40% by age 50 years and 90% by age 70. No differences between affected and unaffected older BRCA1 gene carriers were observed for a number of known epidemiologic risk factors for these cancers. The gender of the parent from whom the mutant BRCA1 allele was inherited was significantly associated with phenotypic expression (P = .04). A recombinant which places BRCA1 distal to the marker Mfd191 was observed.
Women with the BRCA1 mutation are at increased risk of developing breast and ovarian cancer. In our study population, the mutation appears to confer a lower risk of cancer at younger ages than found in previous studies. Continued interaction with family K2082 will be useful in longitudinal follow-up studies and in studies of the psychosocial implications of providing DNA diagnosis of BRCA1.
JNCI Journal of the National Cancer Institute 03/1994; 86(3):200-9. · 14.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper we present linkage results from the analysis of 18 Utah breast cancer kindreds, for three 17q markers. Four kindreds had LOD scores greater than 1.0 for at least one of the marker loci. One of these kindreds has a LOD score of 6.07 with D17S579, and we believe it to be the most informative 17q family reported to date. Among the kindreds which appear unlinked to 17q were an early-onset breast cancer family, a large breast-ovarian family, and a kindred with mixed age at onset. Analysis of individual recombinants in the linked families localizes the BRCA1 gene between THRA1 and D17S579 (Mfd188). A comparison of the Cancer and Steroid Hormone Study (CASH) model and a model which assumes a rare dominant susceptibility locus with low penetrance and no phenocopies stresses the difficulties in assessing linkage if the assumptions of the CASH model in terms of age at onset of breast cancer are not appropriate for the BRCA1 locus. A hypothetical breast cancer pedigree is used to calculate gene carrier probabilities under the CASH model, thereby illustrating some of our concerns regarding the use of this model to detect and exclude 17q linkage in breast cancer families.
The American Journal of Human Genetics 05/1993; 52(4):743-8. · 11.20 Impact Factor