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PubMed2026

RNA splicing evidence enables robust classification of BRCA1 exon 18 variants: Results from the ENIGMA consortium.

The Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) research consortium conducted a comprehensive study to characterize spliceogenic variants in BRCA1 exon 18. The absence of systematic RNA-based assessment for these variants has led to inconsistent interpretation, limiting accurate classification and management of individuals and their families. The splicing profile of 166 variants was assessed using minigene assays; 32 were additionally analyzed in blood-derived RNA from 51 individuals and 18 in mouse embryonic stem cell (mESC)-based assays to evaluate homology-directed repair (HDR) capacity. mRNA assessment by RT-PCR in blood samples and minigene assays showed a significant positive correlation, with splicing analysis in mESCs displaying highly concordant results. The mESC-based HDR assay showed that the in-frame exon 18 skipping (Δ18) transcript encodes a non-functional protein lacking rescue activity. Linear regression analysis using mESC splicing and functional data indicated that ≥59% of full-length (FL) levels and <34% of Δ18 were associated with benign HDR activity. These thresholds differ from those recommended by the ClinGen ENIGMA BRCA1 and BRCA2 Variant Curation Expert Panel American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology (AMP) specifications for applying BP7_strong(RNA): >30% functional transcripts or <70% non-functional transcripts. Incorporation of RNA splicing evidence into variant interpretation increased pathogenic (28.6%-31.7%) and benign (3.7%-24.4%) classifications while reducing likely pathogenic (19.5%-17.7%), uncertain (18.9%-8.5%), and likely benign (29.3%-17.7%) categories. Experimental mRNA profiling impacted the interpretation of 34% of variants and resolved uncertainty in approximately 10% of cases. Exon 18 skipping was less tolerated, indicating that the degree of splice perturbation required to impair BRCA1 function may depend on the nature of the resulting non-functional transcript.

Humans↗

PubMed2006

An increased specificity score matrix for the prediction of SF2/ASF-specific exonic splicing enhancers.

Numerous disease-associated point mutations exert their effects by disrupting the activity of exonic splicing enhancers (ESEs). We previously derived position weight matrices to predict putative ESEs specific for four human SR proteins. The score matrices are part of ESEfinder, an online resource to identify ESEs in query sequences. We have now carried out a refined functional SELEX screen for motifs that can act as ESEs in response to the human SR protein SF2/ASF. The test BRCA1 exon under selection was internal, rather than the 3'-terminal IGHM exon used in our earlier studies. A naturally occurring heptameric ESE in BRCA1 exon 18 was replaced with two libraries of random sequences, one seven nucleotides in length, the other 14. Following three rounds of selection for in vitro splicing via internal exon inclusion, new consensus motifs and score matrices were derived. Many winner sequences were demonstrated to be functional ESEs in S100-extract-complementation assays with recombinant SF2/ASF. Motif-score threshold values were derived from both experimental and statistical analyses. Motif scores were shown to correlate with levels of exon inclusion, both in vitro and in vivo. Our results confirm and extend our earlier data, as many of the same motifs are recognized as ESEs by both the original and our new score matrix, despite the different context used for selection. Finally, we have derived an increased specificity score matrix that incorporates information from both of our SF2/ASF-specific matrices and that accurately predicts the exon-skipping phenotypes of deleterious point mutations.

Alternative Splicing↗

PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗

PubMed2004

[Germline mutations in the BRCA1 and BRCA2 genes from breast cancer families in China Han people].

OBJECTIVE: To detect BRCA1 and BRCA2 gene germline mutation in the Chinese breast cancer families. METHODS: Samples of peripheral blood were collected to prepare genomic DNA by conventional techniques from 15 inherited breast cancer patients from 14 breast cancer families, 76 sporadic breast cancer patients, and 100 healthy controls based on informed consent. Exons 4, 8, 11 and 18 - 20 of BRCA1, and exons 1 - 14, 17 - 24 and 27 of BRCA2, were analyzed using DNA direct sequencing. RESULTS: Six single nucleotide polymorphisms (SNPs) were found on the exon 11 of BRCA1, 2 being silent changes without change of amino acid coding, and 4 with change of amino acid coding among which 2 were polymorphic amino acid alterations and 2 were pathogenic SNPs, i.e. mutational sites. One novel BRCA1 mutation, C1196T (Pro 359 Leu), was identified in a family breast cancer patients, who was diagnosed at the age of 37. Another BRCA1 mutation, Trp 372 stop was found in a breast cancer patient who was diagnosed at the age 29. Eight SNPs were found on the exon3, 10 and 11 of BRCA2, among which 5 were silent changes and 3 were polymorphic amino acid alterations. A1093C (Asn289His) in exon 10 and A 3199G (Asn991Asp) in exon 11 being found simultaneously in the patients of 2 families but not appearing in pool DNA sample, and Asn 371 His appearing as A/C heterozygote in pool DNA sample. CONCLUSION: Two pathogenic SNPs have been found in BRCA1 and may be related to early-onset breast cancer. One of them may be a novel mutation characterized of familial breast cancer in China.

Base Sequence↗

PubMed2004

Novel germline mutations in breast cancer susceptibility genes BRCA1, BRCA2 and p53 gene in breast cancer patients from India.

Mutations in breast cancer susceptibility genes, BRCA1 and BRCA2 account for more than 80% of hereditary breast and ovarian cancers. p53 tumor suppressor gene that controls cellular growth and differentiation is also known to be mutated in more than 50% of human cancers including breast cancer. We have carried out a study on BRCA1 and BRCA2 along with p53 gene mutations in both sporadic as well as familial breast cancer patients from India where breast cancer is fast emerging as a major cancer among premenopausal urban women. We examined 124 untreated primary breast cancer patients comprising 100 sporadic and 24 familial cases including 56 age-matched healthy controls for the presence of BRCA1, BRCA2 and the p53 gene mutations using PCR-SSCP and direct nucleotide sequencing. Certain frequently mutated exons such as 2, 5, 11, 13 and 20 of BRCA1, exons 2, 9, 11 (for 6174delT), 18 and 20 of BRCA2 and 4-9 exons of p53 gene were analyzed in sporadic breast cancer while all 22 coding exons of BRCA1 including its flanking intronic regions along with above mentioned exons of BRCA2 and p53 gene were analyzed in familial breast cancer patients. We identified six patients (25%) with BRCA1 mutation of which three were found to be of novel type one in exon 16 (4956insG) and two in exon 7 (Lys110Thr) (Ser114Pro) out of 24 familial breast cancer patients studied from two different geographic regions/populations of India. Two sisters from a single family (12.5%) out of eight families from Goa with Portuguese colonial origin showed presence of founder Ashkenazi Jewish BRCA1 mutation (185delAG) along with (IVS7 561-34T>C; IVS18 5271 + 66G > A). While from New Delhi, four (25%) of 16 breast cancer families showed BRCA1 mutations; a frame shift protein truncating (4956insG), a transition nonsense (Gln1395Stop) and two amino acid substitutions (Lys110Thr) and (Ser114Pro). Only one (4%) p53 mutation (Val97Ile) in its exon 4 along with BRCA1 mutation (4956insG) could be detected. No major sequence variation in BRCA2 gene was observed except for G203A at 5' UTR of exon 2, a common population polymorphism in two Goan patients who also showed silent nucleotide change for amino acid serine at codon 1436 of BRCA1 gene. None of the 100 sporadic breast cancer patients revealed any protein truncating or deleterious BRCA1 or BRCA2 gene mutation. Interestingly, three (3%) p53 mutations in its exon 5 were detected in sporadic breast cancer patients. Although three novel BRCA1 mutations including a founder Ashkenazi Jewish BRCA1 mutation were recorded in Indian women with familial breast cancer, the overall prevalence of BRCA gene mutations in Indian women with a family history of breast cancer appears to be low.

Adult↗

PubMed2002

Significant contribution of large BRCA1 gene rearrangements in 120 French breast and ovarian cancer families.

Genetic linkage data have shown that alterations of the BRCA1 gene are responsible for the majority of hereditary breast-ovarian cancers. However, BRCA1 germline mutations are found much less frequently than expected, especially as standard PCR-based mutation detection approaches focus on point and small gene alterations. In order to estimate the contribution of large gene rearrangements to the BRCA1 mutation spectrum, we have extensively analysed a series of 120 French breast-ovarian cancer cases. Thirty-eight were previously found carrier of a BRCA1 point mutation, 14 of a BRCA2 point mutation and one case has previously been reported as carrier of a large BRCA1 deletion. The remaining 67 cases were studied using the BRCA1 bar code approach on combed DNA which allows a panoramic view of the BRCA1 region. Three additional rearrangements were detected: a recurrent 23.8 kb deletion of exons 8-13, a 17.2 kb duplication of exons 3-8 and a 8.6 kb duplication of exons 18-20. Thus, in our series, BRCA1 large rearrangements accounted for 3.3% (4/120) of breast-ovarian cancer cases and 9.5% (4/42) of the BRCA1 gene mutation spectrum, suggesting that their screening is an important step that should be now systematically included in genetic testing surveys.

Adult↗

PubMed2004

Characterization of a novel large deletion and single point mutations in the BRCA1 gene in a Greek cohort of families with suspected hereditary breast cancer.

BACKGROUND: Germline mutations in BRCA1 and BRCA2 predispose to breast and ovarian cancer. A multitude of mutations have been described and are found to be scattered throughout these two large genes. We describe analysis of BRCA1 in 25 individuals from 18 families from a Greek cohort. METHODS: The approach used is based on dHPLC mutation screening of the BRCA1 gene, followed by sequencing of fragments suspected to carry a mutation including intron--exon boundaries. In patients with a strong family history but for whom no mutations were detected, analysis was extended to exons 10 and 11 of the BRCA2 gene, followed by MLPA analysis for screening for large genomic rearrangements. RESULTS: A pathogenic mutation in BRCA1 was identified in 5/18 (27.7 %) families, where four distinct mutations have been observed. Single base putative pathogenic mutations were identified by dHPLC and confirmed by sequence analysis in 4 families: 5382insC (in two families), G1738R, and 5586G > A (in one family each). In addition, 18 unclassified variants and silent polymorphisms were detected including a novel silent polymorphism in exon 11 of the BRCA1 gene. Finally, MLPA revealed deletion of exon 20 of the BRCA1 gene in one family, a deletion that encompasses 3.2 kb of the gene starting 21 bases into exon 20 and extending 3.2 kb into intron 20 and leads to skipping of the entire exon 20. The 3' breakpoint lies within an AluSp repeat but there are no recognizable repeat motifs at the 5' breakpoint implicating a mechanism different to Alu-mediated recombination, responsible for the majority of rearrangements in the BRCA1 gene. CONCLUSIONS: We conclude that a combination of techniques capable of detecting both single base mutations and small insertions/deletions and large genomic rearrangements is necessary in order to accurately analyze the BRCA1 gene in patients at high risk of carrying a germline mutation as determined by their family history. Furthermore, our results suggest that in those families with strong evidence of linkage to the BRCA1 locus in whom no point mutation has been identified re-examination should be carried out searching specifically for genomic rearrangements.

Age of Onset↗

PubMed2006

Contribution of germline BRCA1 and BRCA2 sequence alterations to breast cancer in Northern India.

BACKGROUND: A large number of distinct mutations in the BRCA1 and BRCA2 genes have been reported worldwide, but little is known regarding the role of these inherited susceptibility genes in breast cancer risk among Indian women. We investigated the distribution and the nature of BRCA1 and BRCA2 germline mutations and polymorphisms in a cohort of 204 Indian breast cancer patients and 140 age-matched controls. METHOD: Cases were selected with regard to early onset disease (< or =40 years) and family history of breast and ovarian cancer. Two hundred four breast cancer cases along with 140 age-matched controls were analyzed for mutations. All coding regions and exon-intron boundaries of the BRCA1 and BRCA2 genes were screened by heteroduplex analysis followed by direct sequencing of detected variants. RESULTS: In total, 18 genetic alterations were identified. Three deleterious frame-shift mutations (185delAG in exon 2; 4184del4 and 3596del4 in exon 11) were identified in BRCA1, along with one missense mutation (K1667R), one 5'UTR alteration (22C>G), three intronic variants (IVS10-12delG, IVS13+2T>C, IVS7+38T>C) and one silent substitution (5154C>T). Similarly three pathogenic protein-truncating mutations (6376insAA in exon 11, 8576insC in exon19, and 9999delA in exon 27) along with one missense mutation (A2951T), four intronic alterations (IVS2+90T>A, IVS7+75A>T, IVS8+56C>T, IVS25+58insG) and one silent substitution (1593A>G) were identified in BRCA2. Four previously reported polymorphisms (K1183R, S1613G, and M1652I in BRCA1, and 7470A>G in BRCA2) were detected in both controls and breast cancer patients. Rare BRCA1/2 sequence alterations were observed in 15 out of 105 (14.2%) early-onset cases without family history and 11.7% (4/34) breast cancer cases with family history. Of these, six were pathogenic protein truncating mutations. In addition, several variants of uncertain clinical significance were identified. Among these are two missense variants, one alteration of a consensus splice donor sequence, and a variant that potentially disrupts translational initiation. CONCLUSION: BRCA1 and BRCA2 mutations appear to account for a lower proportion of breast cancer patients at increased risk of harboring such mutations in Northern India (6/204, 2.9%) than has been reported in other populations. However, given the limited extent of reported family history among these patients, the observed mutation frequency is not dissimilar from that reported in other cohorts of early onset breast cancer patients. Several of the identified mutations are unique and novel to Indian patients.

Adolescent↗

PubMed2002

Rapid detection of novel BRCA1 rearrangements in high-risk breast-ovarian cancer families using multiplex PCR of short fluorescent fragments.

Recent studies have revealed a significant proportion of BRCA1 exon deletions or duplications in breast-ovarian cancer families with high probability of BRCA1- or BRCA2-linked predisposition, in which mutations of these genes have not been found. The difficulty of detecting such heterozygous rearrangements has stimulated the development of several new screening methods. Quantitative fluorescent multiplex PCR is based on simultaneous amplification of multiple target sequences under conditions that allow rapid and reliable quantitative comparison of the fluorescence of each amplicon in test samples and in controls. The modified method described here, named quantitative multiplex PCR of short fluorescent fragments (QMPSF), is particularly well suited for large genes. All BRCA1 coding exons were analyzed using four multiplexes in 52 families without point mutations in the exons or splice-sites of BRCA1 and BRCA2, and selected because of high probability of a BRCA1- or BRCA2-linked genetic predisposition. Five distinct BRCA1 rearrangements were detected: a deletion of exons 8-13, a duplication of exons 3-8, a duplication of exons 18-20, a deletion of exons 15-16, and a deletion of exons 1-22-which is the largest deletion found so far within the BRCA1 gene. The method described here lends itself to rapid, sensitive, and cost-effective search of BRCA1 rearrangements and may be included into the routine molecular analysis of breast-ovarian cancer predispositions. Hum Mutat 20:218-226, 2002.

BRCA1 Protein↗

PubMed2002

Novel mutations in the BRCA1 and BRCA2 genes in Iranian women with early-onset breast cancer.

BACKGROUND: Breast cancer is the most common female malignancy and a major cause of death in middle-aged women. So far, germline mutations in the BRCA1 and BRCA2 genes in patients with early-onset breast and/or ovarian cancer have not been identified within the Iranian population. METHODS: With the collaboration of two main centres for cancer in Iran, we obtained clinical information, family history and peripheral blood from 83 women under the age of 45 with early-onset breast cancer for scanning of germline mutations in the BRCA1 and BRCA2 genes. We analysed BRCA1 exons 11 and BRCA2 exons 10 and 11 by the protein truncation test, and BRCA1 exons 2, 3, 5, 13 and 20 and BRCA2 exons 9, 17, 18 and 23 with the single-strand conformation polymorphism assay on genomic DNA amplified by polymerase chain reaction. RESULTS: Ten sequence variants were identified: five frameshifts (putative mutations - four novel); three missense changes of unknown significance and two polymorphisms, one seen commonly in both Iranian and British populations. CONCLUSIONS: Identification of these novel mutations suggests that any given population should develop a mutation database for its programme of breast cancer screening. The pattern of mutations seen in the BRCA genes seems not to differ from other populations studied. Early-onset breast cancer (less than 45 years) and a limited family history is sufficient to justify mutation screening with a detection rate of over 25% in this group, whereas sporadic early-onset breast cancer (detection rate less than 5%) is unlikely to be cost-effective.

Adult↗

PubMed2006

Low prevalence of BRCA1 exon rearrangements in familial and young sporadic breast cancer patients.

BRCA1 exon deletions and duplications have been reported in a number of studies, and in order to design an effective mutation screening strategy in a diagnostic setting it is import to determine the frequency of this type of mutation in breast and ovarian cancer patients. We have designed and applied quantitative fluorescent PCR (QF-PCR) assays to screen for BRCA1 exon rearrangements in breast cancer patients both with and without a family history. A panel of 182 familial patients was screened, and an exon 3-7 deletion mutation was detected in a patient with a family history of breast and ovarian cancer. Additionally, we detected a duplication of exons 18-19 in an early onset sporadic breast cancer patient from a panel of 100 patients tested. These data indicate that in the absence of any founder mutations, screening for BRCA1 exon rearrangements does not significantly increase the overall BRCA1 mutation detection rate in patients referred to a genetics clinic because of either a family history and/or an early onset of disease.

Adult↗

PubMed1998

Constant denaturant gel electrophoresis (CDGE) in BRCA1 mutation screening.

Screening for mutations in the breast and ovarian cancer susceptibility gene, BRCA1, is complicated by the wide spectrum of mutations found in this large gene. In the present study a constant denaturant gel electrophoresis (CDGE) mutation screening strategy was established for approximately 80% of the genomic coding sequence (exons 2, 11, 13-16, 20, 24). This strategy was applied to screen genomic DNA from 50 familial breast and/or ovarian cancer patients who had previously been examined for BRCA1 mutations by SSCP. A total of 14 carriers of 12 distinct disease-associated mutations and 7 carriers of 6 distinct rare substitutions leading to amino acid substitutions were identified. The SSCP failed to detect 40% of the different deletions/insertions (4/10) and 75% (6/8) of the different base substitutions leading to terminating codons or rare amino acid changes. SSCP did, however, identify one rare base substitution that could not be detected in the CDGE screening. To evaluate the CDGE mutation screening strategy further, 25 unrelated patients from Norwegian breast and/or ovarian cancer families were examined for BRCA1 mutations using a combined genomic DNA/cDNA approach covering the entire coding sequence of the gene. A total of six mutation carriers were detected, all of whom had cases of ovarian cancer in their families. Three patients from independent families carried an 1135insA mutation in exon 11, two others had a Gly484ter and an 1675delA mutation, respectively, and the sixth carried a splice mutation (5194-2 a-->c) causing deletion of exon 18. CDGE may become an efficient tool in diagnostic and population based screening for BRCA1 mutations.

BRCA1 Protein↗

PubMed2003

Italian family with two independent mutations: 3358T/A in BRCA1 and 8756delA in BRCA2 genes.

Hereditary breast/ovarian cancer is a well-characterized clinical entity, largely attributed to the inheritance of BRCA1 or BRCA2 mutations. Among general population, the mutation's frequency of these genes is very low; therefore, the identification of two independent mutations in the same family is a rare event. This study reports the presence of two mutations, one in the BRCA1 and the second in the BRCA2 gene in an Italian Caucasian kindred. This family is composed of more than 250 individuals, spanning through five generations, among which endogamy was a common phenomenon. Considering the tumor spectrum, this family is characterized by a high incidence of different types of cancer. In our study, we considered only three out of seven family units for BRCA1 and BRCA2 analysis. In one of the family units, we found independent mutations of both BRCA genes. The BRCA1 mutation on exon 11 (3358T-->A) was identified originally in the index case and subsequently in 18 members of this family, whereas the same mutation was not detected in a related family member with male breast cancer. The male breast cancer patient led to the identification, through mutational analysis, of a new BRCA2 mutation (8756delA). This BRCA2 mutation was also found in the male breast cancer patient's daughter. The discovery of the BRCA2 mutation allowed us to alert the patient's daughter who, otherwise, could be falsely reassured since she had a negative BRCA1 test.

Adult↗

PubMed2000

Screening of BRCA1 mutation using immunohistochemical staining with C-terminal and N-terminal antibodies in familial ovarian cancers.

We examined the subcellular localization of BRCA1 proteins using immunohistochemical staining with C-terminal (GLK-2 antibody) and N-terminal (Ab-2 antibody) monoclonal antibodies in 44 familial ovarian cancers. Among these, 24 cases were associated with 13 independent germ-line mutations of BRCA1, and loss of heterozygosity (LOH) at one or more BRCA1 microsatellite markers was found in all 21 informative tumors tested. With GLK-2 antibody, cytoplasmic staining was observed in 15 of 16 tumors (93.8%) with mutation in exon 11, and BRCA1 staining was absent in 8 of 8 tumors (100%) with mutation in exons other than exon 11. When immunohistochemical staining was performed with Ab-2 antibody, both nuclear and cytoplasmic staining were observed in 14 of 16 tumors (87.5%) with mutation in exon 11. Interestingly, nuclear staining was observed in 3 of 3 tumors (100%) with mutation downstream of exon 11, even though no staining was detected in 5 of 5 tumors (100%) with mutation upstream of exon 11. On the other hand, in familial ovarian cancers without BRCA1 mutations, nuclear staining or both nuclear and cytoplasmic staining was observed in 18 of 20 specimens (90%) and 20 of 20 specimens (100%) with GLK-2 antibody and with Ab-2 antibody, respectively. These results suggest that an immunohistochemical assay in combination with employing the C-terminal and the N-terminal antibodies appears to have potential as a reliable and useful technique for the screening of BRCA1 mutations, at least to predict the status of mutation, upstream or downstream of exon 11.

BRCA1 Protein↗

PubMed2004

BRCA1 testing in breast and/or ovarian cancer families from northeastern France identifies two common mutations with a founder effect.

OBJECTIVE: The purpose of this study was to determine whether two mutations detected frequently in a population of breast and/or ovarian cancer families originating from the northeastern part of France could be due to a founder effect. METHODS: 83 index cases of families ascertained to have a familial breast and/or ovarian cancer history, were screened for mutations in all coding exons of the BRCA1 gene, using combined DGGE and direct sequencing. For haplotype analysis, six polymorphic markers were used for allelotyping of mutation carriers and non carriers from nine families with 3600del11 mutation and four families with G1710X mutation. RESULTS: Of 83 index cases, 27 (32%) had 14 different BRCA1 mutations, one of which (G1710X), had not been reported in other populations. Two mutations were particularly common: 3600del11 in exon 11 accounted for 37% and the nonsense mutation G1710X in exon 18 for 15% of all mutations. We identified a common haplotype for each mutation suggesting a common founder for each recurrent mutation. No specific phenotype could be assigned to any of the common mutations. CONCLUSIONS: These data demonstrate geographical clustering and suggest a founder effect for particular BRCA1 mutations, which identification will facilitate carrier detection in French families with breast cancer and breast and/or ovarian cancer.

Adult↗

PubMed1998

Detection of BRCA1 gene mutations in families with breast cancer patients and their healthy relatives.

Eighty-three families with two or more cases of breast and ovarian cancer were selected to evaluate the prevalence rate of BRCA1 gene mutations, and identify healthy carriers. Blood samples from patients and healthy relatives were obtained. Haplotype study of the 17q21 region using 7 polymorphic markers was performed. Mutational analysis of the coding exons of the BRCA1 gene was performed by the PCR-SSCP method and direct sequencing. We detected germline mutations (frameshift and missense) in 6 families (9.1%). Combining haplotype analysis and PCR-SSCP screening, 18 (15%) healthy female carriers were identified. The prevalence rate of germline BRCA1 gene mutations among our families with breast cancer syndrome is low, and relatives having the same haplotype for the 17q21 region as mutation-carrying patients usually display the same genomic sequence as the patients.

Breast Neoplasms↗

PubMed2006

A novel frequent BRCA1 allele in Chinese patients with breast cancer.

The whole length of exon 11 of BRCA1 was sequenced (total 3427 bp) in 59 patients and 10 healthy female blood donors. To allow a rapid determination of the different BRCA1 alleles, a sequence-specific primer PCR method (PCR-SSP) was established and was applied to 57 additional female donors. Finally, the full-length coding region of BRCA1 was analyzed through reversed-transcriptase PCR (RT-PCR) and cDNA sequencing (total 5554 bp) in one donor with wild-type allele and 2 patients with one or two mutated alleles. By genomic DNA sequencing, 5 homozygous polymorphisms were observed in 18 patients: 2201C>T, 2430T>C, 2731C>T, 3232A>G and 3667A>G All of them were previously observed in Caucasians, Malay and Chinese, but for the first time the mutations were found in one allele (GenBank AY304547). Twenty-six patients and 4 donors were heterozygous at these 5 nucleotide positions. The remaining 15 patients and 6 donors showed a sequence identical with the standard BRCA1 gene. Combined the PCR-SSP results and in a summary, 6 of 67 (9.0 %) healthy individuals were homozygous for the mutated allele, whereas 18 of 59 (30.5 %) breast cancer patients were homozygous. A Chi-square test showed a significant correlation between homozygous mutated BRCA1 allele and breast cancer. The cDNA sequencing showed that 2 additional mutations, 4427T>C in exon 13 and 4956A>G in exon 16, were found. A new BRCA1 allele, which is BRCAI-2201T/2430C/2731T/3232G/3667G/4427C/4956G (GenBank AY751490), was found in Chinese. And the homozygote of this mutated allele may implicate a disease-association in Chinese.

Adult↗

PubMedDate not supplied

[Analysis of mutations in the BRCA1 gene in patients with cancer of the breast and/or the ovary in Portugal].

Germline mutations in the BRCA1 gene confer an increased susceptibility to breast and ovarian cancer. Approximately 460 distinct mutations were founded scattered throughout the whole gene. However, several mutations were detected repeatedly in individuals of the same ethnic origin. There are no systematic studies concerning mutations in BRCA1 gene in Portugal. The aim of this study is to identify mutations inh this gene in patients with breast and/or ovarian cancer of Portuguese origin. Thirty-three cases of breast cancer and 3 of ovarian cancer were selected according to early age of onset and family history. Mutation screening of this gene was done by Protein Truncation Test (PTT) and Fragment analysis. Two de novo mutations were identified: 1) A frameshift mutation localised in exon 11 of BRCA1, was identify by the two techniques in an ovarian cancer case. Direct sequential revealed a deletion of 4 nucleotides (3444delAAAT); 2) An alteration in intron 18 (IVS 18 + 80delT) was observed in a breast cancer case. This is probably the first description of mutations in a series of patients with breast and/or cancer in the Portuguese population. The mutations identified in this study have not been previously described in other populations according to the Breast Cancer Information Core web site.

Breast Neoplasms↗