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Exome sequencing of germline DNA from non-BRCA1/2 familial breast cancer cases selected on the basis of aCGH tumor profiling.

ABSTRACT: The bulk of familial breast cancer risk (?70%) cannot be explained by mutations in the known predisposition genes, primarily BRCA1 and BRCA2. Underlying genetic heterogeneity in these cases is the probable explanation for the failure of all attempts to identify further high-risk alleles. While exome sequencing of non-BRCA1/2 breast cancer cases is a promising strategy to detect new high-risk genes, rational approaches to the rigorous pre-selection of cases are needed to reduce heterogeneity. We selected six families in which the tumours of multiple cases showed a specific genomic profile on array comparative genomic hybridization (aCGH). Linkage analysis in these families revealed a region on chromosome 4 with a LOD score of 2.49 under homogeneity. We then analysed the germline DNA of two patients from each family using exome sequencing. Initially focusing on the linkage region, no potentially pathogenic variants could be identified in more than one family. Variants outside the linkage region were then analysed, and we detected multiple possibly pathogenic variants in genes that encode DNA integrity maintenance proteins. However, further analysis led to the rejection of all variants due to poor co-segregation or a relatively high allele frequency in a control population. We concluded that using CGH results to focus on a sub-set of families for sequencing analysis did not enable us to identify a common genetic change responsible for the aggregation of breast cancer in these families. Our data also support the emerging view that non-BRCA1/2 hereditary breast cancer families have a very heterogeneous genetic basis.

SUBMITTER: Hilbers FS

PROVIDER: S-EPMC3561352 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Exome sequencing of germline DNA from non-BRCA1/2 familial breast cancer cases selected on the basis of aCGH tumor profiling.

Hilbers Florentine S FS Meijers Caro M CM Laros Jeroen F J JF van Galen Michiel M Hoogerbrugge Nicoline N Vasen Hans F A HF Nederlof Petra M PM Wijnen Juul T JT van Asperen Christi J CJ Devilee Peter P

PloS one 20130131 1

The bulk of familial breast cancer risk (∼70%) cannot be explained by mutations in the known predisposition genes, primarily BRCA1 and BRCA2. Underlying genetic heterogeneity in these cases is the probable explanation for the failure of all attempts to identify further high-risk alleles. While exome sequencing of non-BRCA1/2 breast cancer cases is a promising strategy to detect new high-risk genes, rational approaches to the rigorous pre-selection of cases are needed to reduce heterogeneity. We ...[more]

PMID: 23383274

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Project description:BackgroundColorectal cancer (CRC) cases with an age of onset <40 years suggests a germline genetic cause. In total, 51 simplex cases were included to test the hypothesis of CRC as a mendelian trait caused by either heterozygous autosomal dominant or bi-allelic autosomal recessive pathogenic variants.MethodsThe cohort was whole exome sequenced (WES) at 100× coverage. Both a dominant- and recessive model were used for searching predisposing genetic factors. In addition, we assayed recessive variants of potential moderate risk that were enriched in our young-onset CRC cohort. Variants were filtered using a candidate cancer gene list or by selecting variants more likely to be pathogenic based on variant type (e.g., loss-of-function) or allele frequency.ResultsWe identified one pathogenic variant in PTEN in a patient subsequently confirmed to have a hereditary hamartoma tumor syndrome (Cowden syndrome) and one patient with a pathogenic heterozygous variant in PMS2 that was originally not identified by WES due to low quality reads resulting from pseudogenes. In addition, we identified three heterozygous candidate missense variants in known cancer susceptibility genes (BMPR1A, BRIP1, and SRC), three truncating variants in possibly novel cancer genes (CLSPN, SEC24B, SSH2) and four candidate missense variants in ACACA, NR2C2, INPP4A, and DIDO1. We also identify five possible autosomal recessive candidate genes: ATP10B, PKHD1, UGGT2, MYH13, TFF3.ConclusionTwo clear pathogenic variants were identified in patients that had not been identified clinically. Thus, the chance of detecting a hereditary cancer syndrome in patients with CRC at young age but without family history is 2/51 (4%) and therefore the clinical benefit of genetic testing in this patient group is low. Of note, using stringent filtering, we have identified a total of ten candidate heterozygous variants and five possibly biallelic autosomal recessive candidate genes that warrant further study.

Dataset Information

Exome sequencing of germline DNA from non-BRCA1/2 familial breast cancer cases selected on the basis of aCGH tumor profiling.

Publications

Exome sequencing of germline DNA from non-BRCA1/2 familial breast cancer cases selected on the basis of aCGH tumor profiling.

Similar Datasets

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