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The use of ultra-dense array CGH analysis for the discovery of micro-copy number alterations and gene fusions in the cancer genome.
BMC Med Genomics. 2011 Jan 27;4(1):16
Authors: Przybytkowski E, Ferrario C, Basik M
ABSTRACT: BACKGROUND: Molecular alterations critical to development of cancer include mutations, copy number alterations (amplifications and deletions) as well as genomic rearrangements resulting in gene fusions. Massively parallel next generation sequencing, which enables the discovery of such changes, uses considerable quantities of genomic DNA (> 5ug), a serious limitation in ever smaller clinical samples. However, a commonly available microarray platforms such as array comparative genomic hybridization (array CGH) allows the characterization of gene copy number at a single gene resolution using much smaller amounts of genomic DNA. In this study we evaluate the sensitivity of ultra-dense array CGH platforms developed by Agilent, especially that of the 1 million probe array (1M array), and their application when whole genome amplification is required because of limited sample quantities. METHODS: We performed array CGH on whole genome amplified and not amplified genomic DNA from MCF-7 breast cancer cells, using 244K and 1M Agilent arrays. The ADM-2 algorithm was used to identify micro-copy number alterations that measured less than 1 Mb in genomic length. RESULTS: DNA from MCF-7 breast cancer cells was analyzed for micro-copy number alterations, defined as measuring less than 1Mb in genomic length. The 4-fold extra resolution of the 1M array platform relative to the less dense 244K array platform, led to the improved detection of copy number variations (CNVs) and micro-CNAs. The identification of intra-genic breakpoints in areas of DNA copy number gain signaled the possible presence of gene fusion events. However, the ultra-dense platforms, especially the densest 1M array, detect artifacts inherent to whole genome amplification and should be used only with non-amplified DNA samples. CONCLUSIONS: This is a first report using 1M array CGH for the discovery of cancer genes and biomarkers. We show the remarkable capacity of this technology to discover CNVs, micro-copy number alterations and even gene fusions. However, these platforms require excellent genomic DNA quality and do not tolerate relatively small imperfections related to the whole genome amplification.
PMID: 21272361 [PubMed - as supplied by publisher]
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The use of ultra-dense array CGH analysis for the discovery of micro-copy number alterations and gene fusions in the cancer genome.
BMC Med Genomics. 2011 Jan 27;4(1):16
Authors: Przybytkowski E, Ferrario C, Basik M
ABSTRACT: BACKGROUND: Molecular alterations critical to development of cancer include mutations, copy number alterations (amplifications and deletions) as well as genomic rearrangements resulting in gene fusions. Massively parallel next generation sequencing, which enables the discovery of such changes, uses considerable quantities of genomic DNA (> 5ug), a serious limitation in ever smaller clinical samples. However, a commonly available microarray platforms such as array comparative genomic hybridization (array CGH) allows the characterization of gene copy number at a single gene resolution using much smaller amounts of genomic DNA. In this study we evaluate the sensitivity of ultra-dense array CGH platforms developed by Agilent, especially that of the 1 million probe array (1M array), and their application when whole genome amplification is required because of limited sample quantities. METHODS: We performed array CGH on whole genome amplified and not amplified genomic DNA from MCF-7 breast cancer cells, using 244K and 1M Agilent arrays. The ADM-2 algorithm was used to identify micro-copy number alterations that measured less than 1 Mb in genomic length. RESULTS: DNA from MCF-7 breast cancer cells was analyzed for micro-copy number alterations, defined as measuring less than 1Mb in genomic length. The 4-fold extra resolution of the 1M array platform relative to the less dense 244K array platform, led to the improved detection of copy number variations (CNVs) and micro-CNAs. The identification of intra-genic breakpoints in areas of DNA copy number gain signaled the possible presence of gene fusion events. However, the ultra-dense platforms, especially the densest 1M array, detect artifacts inherent to whole genome amplification and should be used only with non-amplified DNA samples. CONCLUSIONS: This is a first report using 1M array CGH for the discovery of cancer genes and biomarkers. We show the remarkable capacity of this technology to discover CNVs, micro-copy number alterations and even gene fusions. However, these platforms require excellent genomic DNA quality and do not tolerate relatively small imperfections related to the whole genome amplification.
PMID: 21272361 [PubMed - as supplied by publisher]
More...