Project description:Only about 25% of familial breast cancer is explained by mutations in BRCA1 and BRCA2, fewer by moderate penetrance genes like P53, PTEN, CHEK2, ATM and PALB2 and an unknown fraction by common variants of genes with low penetrance. Evidence suggests that additional dominant breast cancer genes exist and these are referred to as BRCAX. Clinical presentation of families with highly increased incidence of breast cancer that are non-BRCA1/BRCA2, suggests dominant inheritance of such high penetrance breast cancer genes. Because cancer genes often confer a specific clinical presentation (e.g. age of onset, sex-ratio, tissue spectrum) it seems useful to initiate their discovery by such clinical criteria. An earlier linkage study of BRCAX / non-BRCA1/2 breast cancer families aimed to enrich for a common genetic defect by setting stringent inclusion criteria, failed to identify new breast cancer susceptibility loci. Motivated by results of BRCA1 and BRCA2 breast tumors that have characteristic genomic signatures (array-CGH 'phenotypes'), we present the largest dataset to date showing the genomic profiles of 58 BRCAX primary breast tumors by array-CGH and show by unsupervised hierarchical clustering that they form a heterogeneous group with 4 distinct subtypes that are different from (n = 48) sporadic controls. This provides a possible explanation for the lack of high LOD scores in linkage studies. The presence of more than one BRCAX sub-type suggests the existence of more than one BRCAX gene. We propose approaches that can be employed to stratify BRCAX families based on array-CGH data. 58 primary breast carcinomas from non-BRCA1/2 hereditary breast cancer families (HBC) compared to 48 sporadic tumors
Project description:While new defects in BRCA1 are still being found, it is unclear whether current breast cancer diagnostics misses many BRCA1-associated cases. A reliable test that is able to indicate the involvement of BRCA1 deficiency in cancer genesis could support decision making in genetic counselling and clinical management. To find BRCA1-specific markers and explore the effectiveness of the current diagnostic strategy, we designed a classification method, validated it and examined whether we could find BRCA1-like breast tumours in a group of patients initially diagnosed as non-BRCA1/2 mutation carriers. A classifier was built based on array-CGH profiles of 18 BRCA1-related and 32 control breast tumours, and validated on independent sets of 16 BRCA1-related and 16 control breast carcinomas. Subsequently, we applied the classifier to 48 breast tumours of patients from Hereditary Breast and Ovarian Cancer (HBOC) families in whom no germ line BRCA1/BRCA2 mutations were identified. The classifier showed an accuracy of 91% when applied to the validation sets. In 48 non-BRCA1/2 patients, only two breast tumours presented a BRCA1-like CGH profile. Additional evidence for BRCA1 dysfunction was found in one of these tumours. We here describe the specific chromosomal aberrations in BRCA1-related breast carcinomas. We developed a predictive genetic test for BRCA1-association and show that BRCA1-related tumours can still be identified in HBOC families after routine DNA diagnostics.
Project description:89 tumors from women that were eligible for, and subjected to, routine diagnostic testing according to the HBOC criteria but were negative for pathogenic BRCA1/2-mutations or carried an UV in either BRCA1/2 A BRCA2-classifier was built using array-CGH profiles of 28 BRCA2-mutated and 28 sporadic breast tumors. The classifier was validated on an independent group of 19 BRCA2-mutated and 19 sporadic breast tumors. Subsequently, we tested 89 breast tumors from suspected hereditary breast (and ovarian) cancer (HBOC) families, in which either no BRCA1/2 mutation or an UV had been found by routine diagnostics.
Project description:Heredity is a major risk factor for ovarian cancer, but many families escape detection. Refined diagnosis of ovarian cancers linked to the breast and ovarian cancer (HBOC) syndrome and the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome would allow cancer prevention in high risk families. In order to delineate genetic profiles of hereditary ovarian cancer, we applied genome wide array comparative genomic hybridization to 24 sporadic tumors, 12 HBOC associated tumors (BRCA1 mutations) and eight HNPCC associated tumors (mismatch repair gene mutations). Unsupervised cluster analysis identified two distinctive clusters related to genetic complexity. Most sporadic and HBOC associated tumors had complex genetic profiles with multiple gains and losses with an average of 41% of the genome altered, whereas mismatch repair defective tumors had stable genetic profiles, with an average of 18% of the genome altered. Losses of 4q34, 13q12-q32 and 19p13 were overrepresented in the HBOC subset, gains of chromosomes 17 and 19 characterized the HNPCC tumors and gains of 20q11 were more common in the sporadic tumors. The genetic distinction between HBOC and HNPCC associated ovarian cancer suggests that genetic profiles can be applied for refined classification of hereditary cases and reflects tumor development along different genetic pathways.
Project description:The ataxia telangiectasia-mutated (ATM) gene is a moderate-risk breast cancer susceptibility gene; germline loss-of-function variants are found in up to 3% of hereditary breast and ovarian cancer (HBOC) families who undergo genetic testing. So far, no clear molecular features of breast tumors occuring in ATM deleterious variant carriers have been described, but identification of an ATM-associated tumors signature may help patients' management. To characterize hallmarks of ATM-associated tumors, absolute copy number variation and loss of heterozygosity profiles were obtained from the OncoScan SNP array.
Project description:NGS-based multiple gene panel resequencing in combination with a high resolution CGH-array was used to identify genetic risk factors for hereditary breast and/or ovarian cancer in 237 high risk patients who were previously tested negative for pathogenic BRCA1/2 variants. All patients were screened for pathogenic variants in 94 different cancer predisposing genes. We identified 32 pathogenic variants in 14 different genes (ATM, BLM, BRCA1, CDH1, CHEK2, FANCG, FANCM, FH, HRAS, PALB2, PMS2, PTEN, RAD51C and NBN) in 30 patients (12.7%). Two pathogenic BRCA1 variants that were previously undetected due to less comprehensive and sensitive methods were found. Five pathogenic variants are novel, three of which occur in genes yet unrelated to hereditary breast and/or ovarian cancer (FANCG, FH and HRAS). In our cohort we discovered a remarkably high frequency of truncating variants in FANCM (2.1%), which has recently been suggested as a susceptibility gene for hereditary breast cancer. Two patients of our cohort carried two different pathogenic variants each and ten other patients in whom a pathogenic variant was confirmed also harbored a variant of unknown significance in a breast and ovarian cancer susceptibility gene. We were able to identify pathogenic variants predisposing for tumor formation in 12.3% of BRCA1/2 negative breast and/or ovarian cancer patients.
Project description:In more than 70% of families with a strong history of breast and ovarian cancers, pathogenic mutation in BRCA1 or BRCA2 cannot be identified, even though hereditary factors are expected to be involved. It has been proposed that tumors with similar molecular phenotypes also share similar pathophysiological mechanisms. Grouping into molecularly homogeneous subsets may therefore be of potential value for further genetic analysis in order to identify new high penetrance breast cancer genes. In the current study, the aim was to investigate if global RNA profiling can be used to identify functional subgroups within breast tumors from families tested negative for BRCA1/2 germline mutations and how these subgroupings relate to different breast cancer patients within the same family. By analyzing a collection of 70 breast tumor biopsies from 58 families, we show that distinct functional subgroupings, similar to the intrinsic molecular breast cancer subtypes, exist. The distribution of subtypes was markedly different from the distribution found among BRCA1/2 mutation carriers. From 11 breast cancer families, breast tumor biopsies from more than one affected family member were included in the study. Notably, in 8 of these families we found that patients from the same family shared the same tumor subtype, showing a tendency of familial aggregation of tumor subtypes (p-value = 1.7e-3). Our finding indicates involvement of hereditary factors in these families in which family members may carry genetic susceptibility not just to breast cancer but to a particular subtype of breast cancer. Using our previously developed BRCA1/2-signatures, we identified 7 non-BRCA1/2 tumors with a BRCA1-like molecular phenotype and provide evidence for epigenetic inactivation of BRCA1 in three of the tumors. In addition, 7 BRCA2-like tumors were found. This is the first study to provide a biological link between breast cancers from family members of high risk non-BRCA1/2 families in a systematic manner, suggesting that future genetic analysis may benefit from subgrouping families into molecularly homogeneous subtypes in order to identify new high penetrance susceptibility genes. Gene expression profiling of 253 breast tumor samples. Breast tumor tissue from 125 patients with germline mutations in BRCA1 (n = 33) or BRCA2 (n = 22) or with no detectable germline mutation in BRCA1 or BRCA2 (n = 70) were included in the study. Serving as a representative control group, primary breast tumor samples (n = 128) were randomly selected among available samples originating from the same department and time period as for the hereditary samples. The study was conducted using Agilent-029949 Custom SurePrint G3 Human GE 8x60K Microarray platform.