Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Affymetrix SNP array data for low-grade astrocytoma samples

ABSTRACT: Copy number analysis of 21 paediatric low-grade astrocytomas identified a discrete copy number gain of 1.9Mb in chromosome band 7q34. The gain was present in 12/14 cerebellar pilocytic astrocytomas. Subsequent analysis of tumour cDNA indentified a novel gene fusion between KIAA1549 and BRAF in these tumours. Copy number analysis of 21 paediatric low-grade astrocytomas using the Affymetrix GeneChip Human Mapping 250K Nsp Array. This study comprised 14 pilocytic astrocytomas, 4 diffuse astrocytomas, one pilomyxoid astrocytoma, one pilomyxoid glioma and one pleomorphic xanthoastrocytoma. Tumours were compared to the mean of two normal male DNA controls.

ORGANISM(S): Homo sapiens

SUBMITTER: Bryan Young

PROVIDER: E-GEOD-14960 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Activation of the ERK/MAPK pathway: a signature genetic defect in posterior fossa pilocytic astrocytomas.

Forshew Tim T Tatevossian Ruth G RG Lawson Andrew R J AR Ma Jing J Neale Geoff G Ogunkolade Babatunji W BW Jones Tania A TA Aarum Johan J Dalton James J Bailey Simon S Chaplin Tracy T Carter Rowena L RL Gajjar Amar A Broniscer Alberto A Young Bryan D BD Ellison David W DW Sheer Denise D

The Journal of pathology 20090601 2

We report genetic aberrations that activate the ERK/MAP kinase pathway in 100% of posterior fossa pilocytic astrocytomas, with a high frequency of gene fusions between KIAA1549 and BRAF among these tumours. These fusions were identified from analysis of focal copy number gains at 7q34, detected using Affymetrix 250K and 6.0 SNP arrays. PCR and sequencing confirmed the presence of five KIAA1549-BRAF fusion variants, along with a single fusion between SRGAP3 and RAF1. The resulting fusion genes la ...[more]

PMID: 19373855

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Project description:Background: The high incidence of recurrence and unpredictable clinical outcome for paediatric ependymoma reflect the imprecision of current therapeutic staging and need for novel risk stratification markers. Gain of chromosome 1q has been reported as a frequent aberration and correlate of adverse outcome in ependymoma. We therefore evaluated a prognostic role for 1q25 gain across three age-defined European clinical trial cohorts of paediatric intracranial ependymoma. Methods: The frequency of 1q gain in paediatric ependymoma was assessed across 51 tumours (42 primary, 9 recurrent) using Affymetrix® 500K SNP arrays. Gain of 1q25 was evaluated by interphase FISH (iFISH) across 189 primary intracranial ependymomas from children treated on the CCLG/SIOP CNS9204 (n = 60) and BBSFOP (n = 65) adjuvant chemotherapy trials, or with primary post-operative radiotherapy (SIOP CNS9904/RT group, n = 64). Results were correlated with clinical, histological and survival data. Findings: Gain of 1q was the most frequent imbalance in primary (7/42, 17 %) and recurrent ependymomas (3/9, 33 %). Gain of 1q25 was the strongest independent predictor of tumour progression in both CNS9204 (HR 3·36, p = 0·0009) and BBSFOP (HR 4·10, p = 0·0009) trial cohorts. In contrast, 1q25 gain was not prognostic for the older CNS9904/RT only group (PFS: p = 0·37, OS: p = 0·95). Clinical variables implicated in adverse outcome amongst cohorts included incomplete tumour resection and posterior fossa location. Interpretation: This is the first study to prospectively identify then validate a prognostic genomic marker for childhood ependymoma across independent prospective trial groups. 1q25 gain predicts progression in primary chemotherapy cohorts but not those treated by post-operative radiotherapy. We propose 1q25 gain is incorporated as an adverse marker into future European chemotherapeutic clinical trial design. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from flash frozen tumour specimens and patient-matched peripheral blood Copy number analysis of Affymetrix 500K SNP arrays was performed for DNA from 51 ependymomas and 40 constitutional DNA samples. Analysing broad genomic aberrations in 51 paediatric ependymomas, looking particularly at 1q gain.

Project description:Immunoglobulin A Nephropathy (IgAN) is a complex multifactorial disease whose genetic bases remain unknown. Distinct linkage and genome-wide association studies in both familial and sporadic IgAN suggest that there is a strong genetic component in IgAN. In this context, an intriguing role could be ascribed to copy number variants (CNVs) that have been recognized as an important source of genetic variation in humans. Here, we performed a whole-genome screening of CNVs in IgAN patients, their healthy relatives and healthy subjects (HS). A total of 217 individuals consisting of 51 IgAN cases and 166 healthy relatives were included in the initial screening. The high-throughput analysis of structural genetic variations, to find concordant aberrations across classes of samples, identified 178 IgAN-specific aberrations, specifically 114 loss and 64 gain. Several CNVs overlapped with regions evidenced by previous genome-wide genetic studies. Moreover, we found that IgAN patients characterized by deteriorated renal function carried low copy numbers of a CNV in chromosome 3 (chr3_loss:52031010-52260722). This CNV contained the TLR9 gene whose expression significantly correlated with the loss aberration in patients with progressive renal damage. Conversely, IgAN patients with normal renal function had no chr3_loss:52031010-52260722 and the TLR9 mRNA was expressed at the same level as in HS, still maintaining a strong correlation with the CNV. In conclusion, here we performed the first genome-wide CNV study in IgAN identifying some structural variants specific to IgAN patients and providing a collection of new candidate genes and loci that could help to dissect the complex genomic setting of the disease. Moreover, we identified a specific CNV, spanning the TLR9 gene, which could explain the disease severity in IgAN patients. To perform a genome-wide CNV study in IgAN identifying some structural variants specific to IgAN patients and providing a collection of new candidate genes and loci that could help to dissect the complex genomic setting of the disease.

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Dataset Information

Affymetrix SNP array data for low-grade astrocytoma samples

Publications

Activation of the ERK/MAPK pathway: a signature genetic defect in posterior fossa pilocytic astrocytomas.

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