The histologic phenotypes of breast carcinoma occurring before age 40 years in women with and without BRCA1 or BRCA2 germline mutations: a population-based study

BACKGROUND: Women with breast carcinoma diagnosed before age 40 years have a greater prevalence of germline BRCA1 and BRCA2 mutations than women with breast carcinoma diagnosed at older ages. Several recognizable histologic characteristics have been identified in breast carcinoma from studies of BRCA1/2 mutation carriers who belong to multiple-case families. The authors attempted to determine whether breast carcinoma occurring before age 40 years in BRCA1 or BRCA2 mutation carriers who were not selected for family history could be distinguished histologically from one another and from breast carcinoma in women of a similar age without a germline BRCA1 or BRCA2 mutation. METHODS: The study undertook a histologic assessment of breast carcinomas diagnosed before age 40 years identified from a population-based study. RESULTS: Breast carcinoma in BRCA1 mutation carriers was associated with a distinct histologic appearance; these tumors were high grade, and had exceptionally high mean mitotic counts, a syncytial growth pattern, pushing margins, and confluent necrosis. Atypical medullary carcinoma was overrepresented in BRCA1 mutation carriers. All low grade tumors and tumors with low mitotic rates belonged to the group without BRCA1 or BRCA2 mutations. Pleomorphic lobular carcinomas and extensive intraduct carcinomas were more common in BRCA2 mutation carriers. CONCLUSIONS: Breast carcinoma occurring in women with a germline BRCA1 or BRCA2 mutation have recognizable histologic phenotypes, which may be useful in identifying individuals more likely to carry germline mutations. Histologic examination of breast carcinoma should become an important part of the evaluation of women seeking genetic testing for germline mutations in these breast carcinoma susceptibility genes.     

BRCA2 germ-line mutations are frequent in male breast cancer patients without a family history of the disease

Breast cancer is a rare disease in men, affecting less than 0.1% of the male population. Two heritable gene defects have been associated with a predisposition to male breast cancer development, ie., germ-line mutations in the breast cancer susceptibility gene BRCA2 and the androgen receptor (AR) gene. In this study, the entire coding regions of BRCA2 and AR were screened for mutations in 34 consecutive male breast cancer patients. Five different truncating BRCA2 mutations were identified in 7 (21%) of the 34 cases, with all mutations being of germ-line origin. Three of the mutated cases carried the same mutation (4186delG), which has been found earlier in two Swedish families with multiple female breast cancer cases. Haplotype analysis supported a common ancestry of 4186delG. One mutation, 6503delTT, was found in a male carrying also a previously identified COOH-terminal polymorphic stop codon (Lys3326ter). No differences were seen between mutation carriers and noncarriers with respect to clinical stage and estrogen or progesterone receptor status. Mutation carriers tended to be younger at diagnosis. No germ-line AR mutations were found in the present material, but the number of AR polyglutamine repeats tended to be lower among mutation carriers. Most surprisingly, only one of the seven BRCA2 mutation carriers had a positive family history of breast cancer, suggesting a lower penetrance of some BRCA2 mutations or an influence of modifying factors for disease development in males and females. The present study implies that approximately one-fifth of all male breast cancer cases in the Swedish population are due to germ-line BRCA2 mutations.     

BRCA1 mutations in women attending clinics that evaluate the risk of breast cancer

BACKGROUND: To define the incidence of BRCA1 mutations among patients seen in clinics that evaluate the risk of breast cancer, we analyzed DNA samples from women seen in this setting and constructed probability tables to provide estimates of the likelihood of finding a BRCA1 mutation in individual families. METHODS: Clinical information, family histories, and blood for DNA analysis were obtained from 263 women with breast cancer. Conformation-sensitive gel electrophoresis and DNA sequencing were used to identify BRCA1 mutations. RESULTS: BRCA1 mutations were identified in 16 percent of women with a family history of breast cancer. Only 7 percent of women from families with a history of breast cancer but not ovarian cancer had BRCA1 mutations. The rates were higher among women from families with a history of both breast and ovarian cancer. Among family members, an average age of less than 55 years at the diagnosis of breast cancer, the presence of ovarian cancer, the presence of breast and ovarian cancer in the same woman, and Ashkenazi Jewish ancestry were all associated with an increased risk of detecting a BRCA1 mutation. No association was found between the presence of bilateral breast cancer or the number of breast cancers in a family and the detection of a BRCA1 mutation, or between the position of the mutation in the BRCA1 gene and the presence of ovarian cancer in a family. CONCLUSIONS: Among women with breast cancer and a family history of the disease, the percentage with BRCA1 coding-region mutations is less than the 45 percent predicted by genetic-linkage analysis. These results suggest that even in a referral clinic specializing in screening women from high-risk families, the majority of tests for BRCA1 mutations will be negative and therefore uninformative.     

Mutations in BRCA1 and BRCA2 in breast cancer families: are there more breast cancer-susceptibility genes?

To estimate the proportion of breast cancer families due to BRCA1 or BRCA2, we performed mutation screening of the entire coding regions of both genes supplemented with linkage analysis of 31 families, 8 containing male breast cancers and 23 site-specific female breast cancer. A combination of protein-truncation test and SSCP or heteroduplex analyses was used for mutation screening complemented, where possible, by the analysis of expression level of BRCA1 and BRCA2 alleles. Six of the eight families with male breast cancer revealed frameshift mutations, two in BRCA1 and four in BRCA2. Although most families with female site-specific breast cancers were thought to be due to mutations in either BRCA1 or BRCA2, we identified only eight mutations in our series of 23 site-specific female breast cancer families (34%), four in BRCA1 and four in BRCA2. According to the posterior probabilities calculated for mutation-negative families, based on linkage data and mutation screening results, we would expect 8-10 site-specific female breast cancer families of our series to be due to neither BRCA1 nor BRCA2. Thus, our results suggest the existence of at least one more major breast cancer-susceptibility gene.     

Conserved core structure in the internal transcribed spacer 1 of the Schizosaccharomyces pombe precursor ribosomal RNA

We have identified four mutations in each of the breast cancer-susceptibility genes, BRCA1 and BRCA2, in French Canadian breast cancer and breast/ovarian cancer families from Quebec. To identify founder effects, we examined independently ascertained French Canadian cancer families for the distribution of these eight mutations. Mutations were found in 41 of 97 families. Six of eight mutations were observed at least twice. The BRCA1 C4446T mutation was the most common mutation found, followed by the BRCA2 8765delAG mutation. Together, these mutations were found in 28 of 41 families identified to have a mutation. The odds of detection of any of the four BRCA1 mutations was 18.7x greater if one or more cases of ovarian cancer were also present in the family. The odds of detection of any of the four BRCA2 mutations was 5.3x greater if there were at least five cases of breast cancer in the family. Interestingly, the presence of a breast cancer case <36 years of age was strongly predictive of the presence of any of the eight mutations screened. Carriers of the same mutation, from different families, shared similar haplotypes, indicating that the mutant alleles were likely to be identical by descent for a mutation in the founder population. The identification of common BRCA1 and BRCA2 mutations will facilitate carrier detection in French Canadian breast cancer and breast/ovarian cancer families.     

Sequence analysis of BRCA1 and BRCA2: correlation of mutations with family history and ovarian cancer risk

PURPOSE: Previous studies of mutations in BRCA1 or BRCA2 have used detection methods that may underestimate the actual frequency of mutations and have analyzed women using heterogeneous criteria for risk of hereditary cancer. PATIENTS AND METHODS: A total of 238 women with breast cancer before age 50 or ovarian cancer at any age and at least one first- or second-degree relative with either diagnosis underwent sequence analysis of BRCA1 followed by analysis of BRCA2 (except for 27 women who declined analysis of BRCA2 after a deleterious mutation was discovered in BRCA1). Results were correlated with personal and family history of malignancy. RESULTS: Deleterious mutations were identified in 94 (39%) women, including 59 of 117 (50%) from families with ovarian cancer and 35 of 121 (29%) from families without ovarian cancer. Mutations were identified in 14 of 70 (20%) women with just one other relative who developed breast cancer before age 50. In women with breast cancer, mutations in BRCA1 and BRCA2 were associated with a 10-fold increased risk of subsequent ovarian carcinoma (P = .005). CONCLUSION: Because mutations in BRCA1 and BRCA2 in women with breast cancer are associated with an increased risk of ovarian cancer, analysis of these genes should be considered for women diagnosed with breast cancer who have a high probability of carrying a mutation according to the statistical model developed with these data.     

Genetic heterogeneity and penetrance analysis of the BRCA1 and BRCA2 genes in breast cancer families. The Breast Cancer Linkage Consortium

The contribution of BRCA1 and BRCA2 to inherited breast cancer was assessed by linkage and mutation analysis in 237 families, each with at least four cases of breast cancer, collected by the Breast Cancer Linkage Consortium. Families were included without regard to the occurrence of ovarian or other cancers. Overall, disease was linked to BRCA1 in an estimated 52% of families, to BRCA2 in 32% of families, and to neither gene in 16% (95% confidence interval [CI] 6%-28%), suggesting other predisposition genes. The majority (81%) of the breast-ovarian cancer families were due to BRCA1, with most others (14%) due to BRCA2. Conversely, the majority of families with male and female breast cancer were due to BRCA2 (76%). The largest proportion (67%) of families due to other genes was found in families with four or five cases of female breast cancer only. These estimates were not substantially affected either by changing the assumed penetrance model for BRCA1 or by including or excluding BRCA1 mutation data. Among those families with disease due to BRCA1 that were tested by one of the standard screening methods, mutations were detected in the coding sequence or splice sites in an estimated 63% (95% CI 51%-77%). The estimated sensitivity was identical for direct sequencing and other techniques. The penetrance of BRCA2 was estimated by maximizing the LOD score in BRCA2-mutation families, over all possible penetrance functions. The estimated cumulative risk of breast cancer reached 28% (95% CI 9%-44%) by age 50 years and 84% (95% CI 43%-95%) by age 70 years. The corresponding ovarian cancer risks were 0.4% (95% CI 0%-1%) by age 50 years and 27% (95% CI 0%-47%) by age 70 years. The lifetime risk of breast cancer appears similar to the risk in BRCA1 carriers, but there was some suggestion of a lower risk in BRCA2 carriers <50 years of age.     

Screening for genetic risk of breast cancer

Approximately 10 to 15 percent of all breast cancers are thought to be familial and about one third of these cases are due to an inherited mutation in a BRCA1 or BRCA2 breast cancer-susceptibility gene. The lifetime incidence of breast cancer in mutation carriers is above 50 percent, and carriers of BRCA1 mutation also have a substantially increased risk of ovarian cancer. BRCA1 and 2 mutations are associated with early-onset breast cancer, and some experts call for aggressive screening of affected persons. Monthly self-examination of the breasts beginning at age 18 and annual clinical examinations and mammography after age 25 have been recommended but are of unproven benefit. Prophylactic mastectomy and oophorectomy have been advocated by some authorities, but these interventions are disfiguring and for some carriers of the gene, they are unnecessary. The patient's decision to undergo genetic screening is complicated by the technical difficulty of the test, the substantial cost and the still incomplete understanding of the penetrance of disease in known mutation carriers.     

Low incidence of BRCA1 mutations among Italian families with breast and ovarian cancer

Most familial breast or ovarian cancers are thought to be due to highly penetrant mutations in the predisposing genes BRCA1 and BRCA2. The cloning of these genes has opened a new era for the genetic counseling of women with a family history of breast or ovarian cancer. To estimate the incidence of detectable BRCA1 mutations and to define the eligibility criteria for genetic testing in the Italian population, a total of 53 patients belonging to 46 families clustering multiple cases of breast and/or ovarian cancer were investigated. Seven families presented with ovarian cancer only, 16 had both ovarian and breast cancers, and 23 were characterized by breast cancer only. Using a combination of protein truncation test (PTT) and single strand conformational polymorphism (SSCP) analysis followed, when necessary, by direct sequencing, we found 8 distinct mutations, 2 of these not reported before. Five frameshift and 2 nonsense mutations led to a truncated protein. One mutation was a missense substitution involving a cysteine in the zinc finger domain. One variant creating an ETS binding site in intron I was found but its role was not defined. The percentage of families carrying mutations was 17%. Among the families characterized by ovarian cancer only and by breast and ovarian cancer, the percentage of BRCA1 mutations was 57% and 12.5%, respectively. In contrast, the percentage of altered BRCA1 in families with only breast cancers was 9%. In the 46 Italian families studied, BRCA1 mutations were detected in fewer kindreds than those previously hypothesized based on linkage analysis, especially when these were characterized by breast cancers only. Our results indicate that families with a low number of cancer patients should be referred for BRCA1 genetic testing mainly when ovarian cancer is present.     

Characterization of IS1515, a functional insertion sequence in Streptococcus pneumoniae

Several BRCA2 mutations are found to occur in geographically diverse breast and ovarian cancer families. To investigate both mutation origin and mutation-specific phenotypes due to BRCA2, we constructed a haplotype of 10 polymorphic short tandem-repeat (STR) markers flanking the BRCA2 locus, in a set of 111 breast or breast/ovarian cancer families selected for having one of nine recurrent BRCA2 mutations. Six of the individual mutations are estimated to have arisen 400-2,000 years ago. In particular, the 6174delT mutation, found in approximately 1% of individuals of Ashkenazi Jewish ancestry, was estimated to have arisen 29 generations ago (1-LOD support interval 22-38). This is substantially more recent than the estimated age of the BRCA1 185delAG mutation (46 generations), derived from our analogous study of BRCA1 mutations. In general, there was no evidence of multiple origins of identical BRCA2 mutations. Our study data were consistent with the previous report of a higher incidence of ovarian cancer in families with mutations in a 3.3-kb region of exon 11 (the ovarian cancer cluster region [OCCR]) (P=.10); but that higher incidence was not statistically significant. There was significant evidence that age at diagnosis of breast cancer varied by mutation (P<.001), although only 8% of the variance in age at diagnosis could be explained by the specific mutation, and there was no evidence of family-specific effects. When the age at diagnosis of the breast cancer cases was examined by OCCR, cases associated with mutations in the OCCR had a significantly older mean age at diagnosis than was seen in those outside this region (48 years vs. 42 years; P=.0005).     

Global sequence diversity of BRCA2: analysis of 71 breast cancer families and 95 control individuals of worldwide populations

The aim of this study was to evaluate the prevalence of simple sequence variation in the BRCA2 gene. To this end, 71 breast and breast-ovarian cancer (HBC/HBOC) families along with 95 control individuals from a wide range of ethnicities were analyzed by means of denaturing high-performance liquid chromatography (DHPLC) and direct sequence analysis. In the coding (10 257 bp) and non-coding (2799 bp) sequences of BRCA2, 82 sequence variants were identified. Three different, apparently disease-associated BRCA2 mutations were found in six HBC/HBOC families (8%): two splice site mutations in introns 5 and 21, and one frameshift mutation in exon 11. In the coding region, 53 simple sequence variants were found: 35 missense mutations, one 2 bp deletion (CT) resulting in a stop at codon 3364, one nonsense mutation with a stop at codon 3326, one deletion of a complete codon (AAA) resulting in the loss of leucine, and 15 silent mutations. In the non-coding region, 26 polymorphisms were detected. Of the 79 sequence variants that were not obviously disease-associated, eight were detected only in HBC/HBOC families. The remaining 71 variants were identified in both HBC/HBOC families and control individuals. Sixty three sequence variants (80%) were specific for a continent. Forty two percent (33 out of 79) of the sequence variants were detected exclusively in Africa, though only 13% of the 332 chromosomes screened were of African origin. Our data indicate that, in BRCA2, simple sequence variation is frequent [in the coding region 1 in 194 bp (straight theta = 2.2 x 10(-4)), and in the non-coding region 1 in 108 bp (straight theta = 4.4 x 10(-4)), respectively].     

The founder mutations 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 appear in 60% of ovarian cancer and 30% of early-onset breast cancer patients among Ashkenazi women

The mutations 185delAG, 188del11, and 5382insC in the BRCA1 gene and 6174delT in the BRCA2 gene were analyzed in 199 Ashkenazi and 44 non-Ashkenazi Jewish unrelated patients with breast and/or ovarian cancer. Of the Jewish Ashkenazi women with ovarian cancer, 62% (13/21) had one of the target mutations, as did 30% (13/43) of women with breast cancer alone diagnosed before the age 40 years and 10% (15/141) of those with breast cancer diagnosed after the age 40 years. Age at ovarian cancer diagnosis was not associated with carrier status. Of 99 Ashkenazi patients with no family history of breast and/or ovarian cancer, 10% carried one of the mutations; in two of them the mutation was proved to be paternally transmitted. One non-Ashkenazi Jewish ovarian cancer patient from Iraq carried the 185delAG mutation. Individual mutation frequencies among breast cancer Ashkenazi patients were 6.7% for 185delAG, 2.2% for 5382insC, and 4.5% for 6174delT, among ovarian cancer patients; 185delAG and 6174delT were about equally common (33% and 29%, respectively), but no ovarian cancer patient carried the 5382insC. More mutations responsible for inherited breast and ovarian cancer probably remain to be found in this population, since 79% of high-incidence breast cancer families and 35% of high-incidence breast/ovarian cancer families had none of the three known founder mutations.     

BRCA1 and BRCA2 in breast cancer families from Wales: moderate mutation frequency and two recurrent mutations in BRCA1

Mutations in the BRCA1/BRCA2 genes account for varying proportions of breast cancer families studied, and demonstrate considerable variation in mutational spectra coincident with ethnic and geographical diversity. We have screened for mutations in 17 families from Wales with two or more cases of breast cancer under age 50 and/or ovarian cancer. Eight out of 17 (47%) families had demonstrable mutations. Six out of 17 (35%) carried BRCA1 mutations and 2 out of 17 (12%) carried BRCA2 mutations. Two recurrent mutations in BRCA1 were identified, which appear to represent founder mutations in this population. These data support the existence of additional breast and ovarian cancer susceptibility genes.     

BRCA1 mutations in southern England

If genetic testing for breast and ovarian cancer predisposition is to become available within a public health care system there needs to be a rational and cost-effective approach to mutation analysis. We have screened for BRCA1 mutations in 230 women with breast cancer, all from the Wessex region of southern England, in order to establish the parameters on which to base a cost-effective regional mutation analysis strategy. Truncating mutations were detected in 10/155 (6.5%) consecutive cases selected only for diagnosis under the age of 40 (nine of these ten women had a strong family history of breast or ovarian cancer), 3/61 (4.9%) bilateral-breast cancer cases (all three mutations occurring among women for whom the first cancer was diagnosed under 40 years) and 8/30 (26.6%) breast cancer cases presenting to the genetics clinic (for whom a strong family history of breast and/or ovarian cancer was present). Ten different mutations were detected in 17 families, but three of these accounted for 10/17 (59%) of the families. The cost of screening the population for mutations in the entire BRCA1 gene is unacceptably high. However, the cost of screening a carefully selected patient cohort is low, the risk of misinterpretation much less and the potential clinical benefits clearer.     

Identifying the patient with severe acute pancreatitis

Epidemiological studies have demonstrated a clustering of breast and prostate cancers in some families. Moreover, there is an increase in the number of cases of prostate cancer in families with inherited mutations of the breast cancer susceptibility gene BRCA1. We assessed the role of BRCA1 and BRCA2 in prostate cancer. We tested for the BRCA1 185delAG frameshift mutation, found in 0.9% of Ashkenazi Jews, and the BRCA2 6174delT mutation, found in 1% of Ashkenazi Jews, in Ashkenazi Jewish men with prostate cancer. We studied 60 Ashkenazi men with prostate cancer. A family history was obtained by interview or a self-report questionnaire. Histological confirmation of diagnosis was obtained for all subjects. Ethnic background was confirmed for all subjects by self-report or interview. Mutations of BRCA1 and BRCA2 were detected by amplification of lymphocyte DNA from peripheral blood according to standard polymerase chain reaction (PCR) and dot blot procedures. Patients' ages ranged from 55 to 80 years (mean +/- s.d. 70 +/- 5.25). There were six men with a family history of prostate cancer; three of these had a father with prostate cancer. Five of the men had a family history of breast cancer, in a mother, a sister or an aunt. None of the men had a family history of both breast and prostate cancer. None of the 60 men carried the 185delAG BRCA1 or 6174delT BRCA2 mutations. Of 268 Ashkenazi Jewish women with sporadic breast cancer, tested in an unrelated study, 16 carried either the 185delAG mutation of BRCA1 or the 6174delT mutation of BRCA2. There was a significant difference in the incidence of the BRCA1 and BRCA2 mutations in the breast and prostate cancer cases (P = 0.05, two-tailed Fisher's exact test). The contribution of germline BRCA1 and BRCA2 mutations to prostate cancer incidence is probably small and could be limited to specific subgroups.     

A high proportion of novel mutations in BRCA1 with strong founder effects among Dutch and Belgian hereditary breast and ovarian cancer families

We have identified 79 mutations in BRCA1 in a set of 643 Dutch and 23 Belgian hereditary breast and ovarian cancer families collected either for research or for clinical diagnostic purposes. Twenty-eight distinct mutations have been observed, 18 of them not previously reported and 12 of them occurring more than once. Most conspicuously, a 2804delAA mutation has been found 19 times and has never been reported outside the Netherlands. A common haplotype spanning > or = 375 kb could be identified for each of the nine examined recurrent mutations, indicating the presence of multiple BRCA1 founder mutations in the Dutch population. The 2804delAA mutation has been estimated to have originated approximately 32 generations ago. No specific breast or ovarian cancer phenotype could be assigned to any of the common mutations, and the ovarian cancer incidence among 18 families with the 2804delAA mutation was heterogeneous.     

Differential contributions of BRCA1 and BRCA2 to early-onset breast cancer

BACKGROUND: Germ-line mutations in the BRCA1 and BRCA2 genes predispose women to breast cancer. BRCA1 mutations are found in approximately 12 percent of women with breast cancer of early onset, and the specific mutation causing a deletion of adenine and guanine (185delAG), which is present in 1 percent of the Ashkenazi Jewish population, contributes to 21 percent of breast cancers among young Jewish women. The contribution of BRCA2 mutations to breast cancer of early onset is unknown. METHODS: Lymphocyte specimens from 73 women with breast cancer diagnosed by the age of 32 were studied for heterozygous mutations of BRCA2 by a complementary-DNA-based protein-truncation assay, followed by automated nucleotide sequencing. In addition, specimens from 39 Jewish women with breast cancer diagnosed by the age of 40 were tested for specific mutations by an allele-specific polymerase chain reaction. RESULTS: Definite BRCA2 mutations were found in 2 of the 73 women with early-onset breast cancer (2.7 percent; 95 percent confidence interval, 0.4 to 9.6 percent), suggesting that BRCA2 is associated with fewer cases than BRCA1 (P=0.03). The specific BRCA2 mutation causing a deletion of thymine (6174delT), which is found in 1.3 percent of the Ashkenazi Jewish population, was observed in 1 of the 39 young Jewish women with breast cancer (2.6 percent; 95 percent confidence interval, 0.09 to 13.5 percent), indicating that it has a small role as a risk factor for early-onset breast cancer. Among young women with breast cancer, there are BRCA2 mutations that cause truncation of the extreme C terminus of the protein and that may be functionally silent, along with definite truncating mutations. CONCLUSIONS: Germ-line mutations in BRCA2 contribute to fewer cases of breast cancer among young women than do mutations in BRCA1. Carriers of BRCA2 mutations may have a smaller increase in the risk of early-onset breast cancer.     

Characteristics of airway colonization in mechanically ventilated newborn infants

A predominant mutation within the BRCA1 predisposition gene, 185delAG, has been detected in about 1% of the Ashkenazi population, considered a high-risk group for breast and ovarian cancers. We examined 639 unrelated healthy Jews of Iraqi extraction, a presumed low-risk group, for the existence of this mutation. Three individuals were identified as 185delAG mutation carriers, and haplotype analysis of the Iraqi mutation carriers revealed that 2 of the Iraqis shared a common haplotype with 6 Ashkenazi mutation carriers, and 1 had a haplotype which differed by a single marker. This study suggests that the BRCA1 185delAG mutation also occurs in populations considered at low-risk for breast and ovarian cancers, and that it might have occurred prior to the dispersion of the Jewish people in the Diaspora, at least at the time of Christ.