Genomic characterization implicates iAMP21 as a primary genetic event in childhood B-cell precursor acute lymphoblastic leukaemia
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE26192 | GEO | 2012/03/02
SECONDARY ACCESSION(S): PRJNA135021
REPOSITORIES: GEO
Similar Datasets
Project description:Intrachromosomal amplification of chromosome 21 (iAMP21) defines a distinct subgroup of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) shown to have a dismal outcome on standard therapy. For improved diagnosis and prognosis of these patients, the initiating genetic events need to be elucidated. To investigate the genetic basis, the genomes of 94 iAMP21 patients were interrogated by genomic arrays, FISH and MLPA. Detailed mapping of chromosome 21 refined the common region of amplification (CRA) to 5.1 Mb; including the RUNX1 gene, miR-802 and genes mapping to the Down Syndrome Critical Region. Over a quarter of copy number alterations targeted chromosome 21, including telomeric deletions in 88% of patients. Global analysis by genomic arrays identified recurrent abnormalities affecting genes in key pathways. The frequency of these abnormalities were determined by FISH and/or MLPA; IKZF1 (22%), CDKN2A/B (17%), PAX5 (8%), ETV6 (19%) and RB1 (37%). Study of the clonal architecture provided evidence that these abnormalities, and P2RY8-CRLF2, were secondary to chromosome 21 instability. This study provides convincing evidence that chromosome 21 instability is the only abnormality common to all iAMP21 patients and the initiating event is likely hidden within the complex structural rearrangements of this abnormal chromosome. DNA copy number analysis of 17 diagnostic and 1 relapse acute lymphoblastic leukaemia samples was performed using agilent 185K microarrays. These samples were hybridised against gender matched reference DNA.
2012-03-02 | E-GEOD-26192 | biostudies-arrayexpress
Project description:Intragenic PAX5 amplification in <1%of B-cell precursor acute lymphoblastic leukaemia. Affymetrix SNP 6.0 array analysis was undertaken in patients who showed amplication of PAX5 by MLPA testing using the P335-IKZF1 MLPA kit (www.mlpa.com, MRC Holland, The Netherlands)
2017-06-09 | GSE99813 | GEO
Project description:Purpose: The purpose of this study was to evaluate SNP genotyping methodology as a means to detect chromosomal abnormalities previously diagnosed by G-band karyotype or fluorescence in situ hybridization (FISH) analysis and to determine the frequency of sub-microscopic (cryptic) chromosomal alterations in these subjects. Methods: We used the Illumina HumanHap Beadchip platform to genotype 40 individuals having previously detected chromosomal anomalies (by G-banded and/or FISH analysis). The resulting data were analyzed for signal intensity (log R ratio) and allelic composition (B allele frequency). Results: SNP array analysis detected 100% of previously identified cytogenetic abnormalities. Changes or clarifications of the ISCN karyotype designation assigned by conventional cytogenetic and/or FISH analysis were made in 82 % of the cases (32 of 39). Nine of the 39 cases (23%) involved a reassignment of an abnormal band while an additional 9 of the 39 (23%) resulted in a clarification of a sub-band assignment. In 8 more of the 39 cases (21%) the previously reported alterations were confirmed, however the SNP analysis also identified related cryptic alterations. SNP analysis not only confirmed FISH-detected abnormalities but also more precisely mapped the breakpoints of 6/6 patients. Investigations into the origin of de novo abnormalities in 15 trio families established that 12 /15 occurred on the paternal chromosome. Conclusions: SNP genotyping array analysis, confirmed all previously detected structural chromosomal abnormalities and provided additional, clinically-relevant genomic information in 82% of these alterations. To evaluate potential chromosomal abnormalities in patients, we measured SNPs using Illumina 550K and 300K arrays. In some cases we also measured SNPs in parents to determine whether deletions or duplications occurred de novo or were inherited.
2011-02-22 | E-GEOD-20623 | biostudies-arrayexpress
Project description:Retinoblastoma (RB, OMIM:180200) is the most common malignant childhood tumor of the eye with an estimated incidence between 1 in 16,000 and 1 in 18,000 live births [1,2]. RB is the first disease for which a genetic etiology of cancer has been described [3] being caused by mutations in the first tumor suppressor gene identified (RB1, Genbank accession # L11910). Mutations in both alleles of the RB1 gene are required for the development of this neoplasm [4], and, depending on the germ-line or somatic origin of the defect, a heritable or sporadic form can be distinguished. RB is unilateral in 60% of cases and only 15% of these are heritable [5]; in contrast, 40% of retinoblastomas are bilateral with risk of transmission to the offspring. Heritable retinoblastoma constitutes a cancer predisposition syndrome [6]. RB1 is located on chromosome 13 at band q14 and can be affected by a heterogeneous spectrum of genetic abnormalities, including chromosome translocation/deletion, genomic rearrangements, ranging from whole gene microdeletion to intragenic exons loss or duplication, and more than 900 different point mutations [7]. Mutational analysis is performed to search for the predisposing RB1 gene mutation in peripheral blood of patients with RB, but the molecular diagnosis requires several technical approaches to cover the entire field of oncogenic RB1 defects, frequently resulting in numerous, expensive and time consuming procedures. In particular, cytogenetic tools, such as classical chromosome investigations and Fluorescent In Situ Hybridization (FISH), in addition to Multiplex Ligation-dependent Probe Amplification (MLPA) technique, may account for detection of about 16% of RB1 abnormalities [8], while the remaining large amount of point mutations need to be investigated using sequencing analysis. Since the 1970s, Sanger sequencing has been recognized as the gold standard for mutation analysis in molecular diagnostics; however, its low-throughput, long turnaround time and overall cost [9] have called for new paradigms. Next Generation Sequencing (NGS) can massively sequence millions of DNA segments, promising low costs, increased workflow speed and enhanced sensitivity in mutation detection [9,10,11] On the other hand, conventional and molecular cytogenetic analysis, have been replaced by modern high-throughput investigations, such as array Comparative Genomic Hybridization (aCGH), that can reveal and measure cryptic genomic imbalances. In addition, aCGH can be focused on specific DNA segments or genes maximizing the resolution via a customized process. Based on these observations, we have recruited a cohort of retinoblastoma patients we previously investigated with conventional cytogenetics and MLPA. Patients diagnosed with RB but negative to the above standard screening have been tested with NGS to assess its ability in identifying RB causative mutations. On the other hand, patients positive to standard screening have been further investigated with RB1-custom array CGH analysis to characterize the genomic rearrangements with a better resolution compared to the conventional techniques. The complementary aCGH data set related to this study has also been deposited at ArrayExpress, under accession number E-MTAB-3492: https://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-3492/
2015-10-31 | E-MTAB-3515 | biostudies-arrayexpress
Project description:Purpose: The purpose of this study was to evaluate SNP genotyping methodology as a means to detect chromosomal abnormalities previously diagnosed by G-band karyotype or fluorescence in situ hybridization (FISH) analysis and to determine the frequency of sub-microscopic (cryptic) chromosomal alterations in these subjects. Methods: We used the Illumina HumanHap Beadchip platform to genotype 40 individuals having previously detected chromosomal anomalies (by G-banded and/or FISH analysis). The resulting data were analyzed for signal intensity (log R ratio) and allelic composition (B allele frequency). Results: SNP array analysis detected 100% of previously identified cytogenetic abnormalities. Changes or clarifications of the ISCN karyotype designation assigned by conventional cytogenetic and/or FISH analysis were made in 82 % of the cases (32 of 39). Nine of the 39 cases (23%) involved a reassignment of an abnormal band while an additional 9 of the 39 (23%) resulted in a clarification of a sub-band assignment. In 8 more of the 39 cases (21%) the previously reported alterations were confirmed, however the SNP analysis also identified related cryptic alterations. SNP analysis not only confirmed FISH-detected abnormalities but also more precisely mapped the breakpoints of 6/6 patients. Investigations into the origin of de novo abnormalities in 15 trio families established that 12 /15 occurred on the paternal chromosome. Conclusions: SNP genotyping array analysis, confirmed all previously detected structural chromosomal abnormalities and provided additional, clinically-relevant genomic information in 82% of these alterations.
2011-02-22 | GSE20623 | GEO
Project description:Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 69 cases with unbalanced insertions identified using array CGH and FISH, representing 1.25% of 5,683 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests the phenotypic consequences may be benign. Moreover, cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification and array CGH we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification coupled with array CGH or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion.
2011-02-28 | GSE27080 | GEO
Project description:Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 69 cases with unbalanced insertions identified using array CGH and FISH, representing 1.25% of 5,683 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests the phenotypic consequences may be benign. Moreover, cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification and array CGH we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification coupled with array CGH or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion. 88 total samples analyzed. No replicates included. Each sample run against a standard sex-matched control.
2011-02-28 | E-GEOD-27080 | biostudies-arrayexpress
Project description:Vascular remodeling in pulmonary arterial hypertension (PAH) involves proliferation and migration of endothelial and smooth muscle cells, leading to obliterative vascular lesions. Previous studies have indicated that the endothelial cell proliferation is quasi-neoplastic, with evidence of monoclonality and instability of short DNA microsatellite sequences. To assess whether there is larger scale genomic instability, we performed genome-wide microarray copy number analysis on pulmonary artery endothelial (PAEC) and smooth muscle cells isolated from the lungs of PAH patients. Mosaic chromosomal abnormalities were detected in five of nine PAEC cultures from PAH lungs and zero of four controls. Fluorescent in situ hybridization analysis confirmed the presence of these abnormalities in vivo in two of three cases. One patient harbored a germline mutation of BMPR2, the primary genetic cause of PAH, and a somatic loss of chromosome-13, which constitutes a second hit in the same pathway by deleting Smad-8. In two female cases with mosaic loss of the X-chromosome, methylation analysis showed that the active X was deleted. Remarkably, one also showed completely skewed X-inactivation in the non-deleted cells, suggesting the PAEC population was clonal prior to the acquisition of the chromosome abnormality. Our data indicate a high frequency of genetically abnormal sub-clones within the lung vessels of patients with PAH and provide the first definitive evidence of a second genetic hit in a patient with a germline BMPR2 mutation. We propose that these chromosome abnormalities may confer a growth advantage and thus contribute to the progression of PAH. Cross-sectional study of genomic copy number in cells cultured from the lungs of PAH patients.
2010-05-01 | E-GEOD-21097 | biostudies-arrayexpress
Project description:G-banding of human embryonic stem cells (hESC) has proved their predisposition to aneuploidy of chromosomes 12, 17 and X. Now, using array-based comparative genomic hybridization, we find that hESC also accumulate other recurrent chromosomal abnormalities, such as duplications of stemness genes, submicroscopic instability of 20q11.21 and the appearance of a derivative chromosome 18. Keywords: comparative genomic hybridization, genomic integrity of human embryonic stem cells Array-based comparative genomic hybridization was performed on 48 DNA samples from 17 human embryonic stem cell lines, all cultured in our laboratory under the same conditions. All lines were hybridized against DNA obtained from peripheral blood from donors with a known normal karyotype. No replicates were done from the same DNA sample, but, whenever possible the same stem cell line was analysed at later passages. All detected abnormalities were confirmed by FISH and/or G-banding.
2010-05-17 | E-GEOD-13422 | biostudies-arrayexpress
Project description:Down syndrome (DS, trisomy 21) is associated with developmental abnormalities and increased leukemia risk. To reconcile chromatin alterations with transcriptome changes in cells with trisomy 21, we performed paired exogenous spike-in normalized RNA and chromatin immunoprecipitation sequencing in DS models. Absolute per cell normalization unmasked global amplification of gene expression associated with trisomy 21. Overexpression of the nucleosome binding protein HMGN1 (encoded on chr21q22) recapitulated the transcriptional changes seen with triplication of a “Down syndrome critical region” on distal chromosome 21. Absolute exogenous normalized ChIP-seq (ChIP-Rx) also revealed a global increase in histone 3 lysine 27 acetylation caused by HMGN1. Genes most amplified downstream of HMGN1 were enriched for tumor- and developmental stage-specific programs of B-cell acute lymphoblastic leukemia dependent on the cellular context. These data offer a mechanistic explanation for DS transcriptional patterns, and suggest that further study of HMGN1 and RNA amplification in diverse DS phenotypes is warranted.
2018-11-13 | GSE121070 | GEO