Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Identification of candidate predisposing copy number variants in familial and early-onset colorectal cancer patients

ABSTRACT: In the majority of colorectal cancers (CRC) under clinical suspicion for a hereditary cause, the disease-causing genetic factors are still to be discovered. In order to identify such genetic factors we stringently selected a discovery cohort of 41 CRC index patients with microsatellite-stable tumors. All patients were below 40 years of age at diagnosis and/or exhibited an overt family history. We employed genome-wide copy number profiling using high-resolution SNP-based array CGH on germline DNA, which resulted in the identification of novel copy number variants (CNVs) in 6 patients (15%) encompassing, among others, the cadherin gene CDH18, the bone morphogenetic protein antagonist family gene GREM1, and the breakpoint cluster region gene BCR. In addition, two genomic deletions were encountered encompassing two microRNA genes, hsa-mir-491/KIAA1797 and hsa-mir-646/AK309218. None of these CNVs has previously been reported in relation to CRC predisposition in humans, nor were they encountered in large control cohorts (>1,600 unaffected individuals). Since several of these newly identified candidate genes may be functionally linked to CRC development, our results illustrate the potential of this approach for the identification of novel candidate genes involved in CRC predisposition. Copy number detection was performed using CNAG2.0 software for 250k SNP arrays and using the Affymetrix Genotyping Console v2.1 software for SNP 6.0 arrays, Reference genomes are included in this data set. Germline genomic DNA from 41 patients with early-onset microsatellite stable colorectal cancer was hybridized on Affymetrix Nsp/6.0 SNP-based arrays according to manufacturer's procedures.

ORGANISM(S): Homo sapiens

SUBMITTER: Roland Kuiper

PROVIDER: E-GEOD-13429 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Identification of candidate predisposing copy number variants in familial and early-onset colorectal cancer patients.

Venkatachalam Ramprasath R Verwiel Eugène T P ET Kamping Eveline J EJ Hoenselaar Eveline E Görgens Heike H Schackert Hans K HK van Krieken J Han J M JH Ligtenberg Marjolijn J L MJ Hoogerbrugge Nicoline N van Kessel Ad Geurts AG Kuiper Roland P RP

International journal of cancer 20110404 7

In the majority of colorectal cancers (CRCs) under clinical suspicion for a hereditary cause, the disease-causing genetic factors are still to be discovered. To identify such genetic factors we stringently selected a discovery cohort of 41 CRC index patients with microsatellite-stable tumors. All patients were below 40 years of age at diagnosis and/or exhibited an overt family history. We employed genome-wide copy number profiling using high-resolution SNP arrays on germline DNA, which resulted ...[more]

PMID: 21128281

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Project description:Many studies estimate that chromosomal mosaicism within the cleavage stage human embryo is high. However, comparison of two unique methods of aneuploidy screening of blastomeres within the same embryo has not been conducted and may indicate whether mosaicism is overestimated due to technical inconsistency rather than biological phenomena. The present study investigates the prevalence of chromosomal abnormality and mosaicism found with two different single cell aneuploidy screening techniques.Thirteen arrested cleavage stage embryos were studied. Each was biopsied into individual cells (n=160). The cells from each embryo were randomized into two groups. Those destined for FISH based aneuploidy screening (n=75) were fixed, 1 cell per slide. Cells for SNP microarray based aneuploidy screening (n=85) were put into individual tubes. Microarray was significantly more reliable (96%) than FISH (83%) for providing an interpretable result (P=0.004). Markedly different results were obtained when comparing microarray and FISH results from individual embryos. Mosaicism was significantly less commonly observed by microarray (4 of 13 embryos; 31%) than by FISH (13 of 13 embryos; 100%)(P=0.0005). Although FISH evaluated fewer chromosomes per cell and fewer cells per embryo, FISH still displayed significantly more unique genetic diagnoses per embryo (3.2+0.2) than microarray (1.3+0.2)(P<0.0001). This is the first prospective, randomized, blinded, and paired comparison between microarray and FISH based aneuploidy screening. Aneuploidy and mosaicism were less common with microarray. While evaluating a smaller number of chromosomes with a proportionally smaller opportunity for finding mosaicism, FISH still had a dramatically higher level of inter-cell variation in diagnosis. SNP microarray based 24 chromosome aneuploidy screening provides more complete and consistent results than FISH. Affymetrix SNP arrays were processed according to the manufacturer's directions on DNA extracted from 13 arrested cleavage stage embryos and biopsied into individual blastomere cells. Individual blastomeres were randomized and blinded for SNP microarray analysis (n = 85). Afflymetrix SNP array analysis was successfully completed on 82 blastomeres.

Project description:Primitive neuro-ectodermal tumours (PNET) of the supratentorial region are rare, highly malignant embryonal brain tumours affecting young children. Although supratentorial PNET (sPNET) are histologically similar to infratentorial PNET/medulloblastoma, sPNET have more aggressive clinical phenotypes, which suggest sPNET represents distinct biological entities. In contrast to considerable progress in understanding the signalling pathways involved in medulloblastoma, little is known about sPNET pathogenesis. Prior low resolution CGH (comparative genomic hybridization) studies indicate sPNET have frequent genomic imbalances and copy number aberrations (CNAs). To define genes involved in sPNET pathogenesis, we utilized the Affymetrix 250K Nsp SNP (single nucleotide polymorphism) analysis to identify genes targeted by recurrent CNAs in primary human sPNET samples. Copy number analysis was conducted on 39 primary PNET samples. Select target genes were validated by genomic and/or RT-PCR. Our analysis revealed frequent CNA across the sPNET genome, encompassing large and focal chromosome segments, and corroborated previous reports that isochromosome 17q, an abnormality found in ~ 30% of medulloblastoma, is rare in sPNET. Keywords: single nucleotide polymorphism array, disease state analysis A total of 56 primary sPNET samples were collected for this study from The Hospital for Sick Children, John Hopkins University, St. Jude Research Hospital, University of Cambridge, Children’s Hospital Boston, Virginia Commonwealth University, Instituto nazionale per lo studio e la cura dei tumori, and Texas Children’s Hospital, with local Institutional Research Ethics Board approval. Pineoblastoma and rhaboid tumours were specifically excluded, leaving 52 samples, 39 of which had good quality DNA available. These samples, in addition to 28 diploid reference samples (a gift from Dr. S. Scherer, University of Toronto), were analyzed on the Affymetrix GeneChip Mapping 250K Nsp SNP array. Due to sample availability at the time the arrays were run, the diploid reference samples analyzed on the Sty arrays are different from reference samples analyzed on the Nsp arrays.

Dataset Information

Identification of candidate predisposing copy number variants in familial and early-onset colorectal cancer patients

Publications

Identification of candidate predisposing copy number variants in familial and early-onset colorectal cancer patients.

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