Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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An experimental loop design improves the detection of congenital chromosomal aberrations by array CGH

ABSTRACT: Comparative genomic hybridization microarrays (array CGH or molecular karyotyping) for the detection of congenital chromosomal aberrations is the application of microarray technology that is coming fastest into routine clinical application. When using a two-channel microarray of genomic DNA probes for array CGH, the basic setup consists in hybridizing a patient sample against a normal reference sample and detecting copy number variations through the deviation of fluorescent signal intensity between patient and normal reference. Two major disadvantages of this setup are (1) the use of half of the resources to measure a (little informative) reference sample and (2) the possibility that deviating signals are caused by benign copy number variation in the ânormalâ reference instead of a patient aberration. We therefore propose a new experimental loop design that compares three patients in three hybridizations (Patient 1 vs. Patient 3, Patient 3 vs. Patient 2, and Patient 2 vs. Patient 1). We develop and compare two statistical methods (linear models of log ratios and mixed models of absolute measurements). In an analysis of data from 27 patients seen at our genetics center, this new setup together with the linear model analysis significantly overcomes the limitations of the classical setup. Furthermore, we observed that the linear models of the log-ratios had a higher signal-to-noise ratio than the mixed models of the absolute intensities. These improvements are important to guarantee a maximal efficiency of array CGH in a clinical setting and will therefore contribute to its quick adoption as a routine diagnostic tool. The method is implemented as a web application and is available at www.esat.kuleuven.be/loop. Keywords: comparative genomic hybridization The data set consists out of nine loop designs or 27 patients with mental retardation (MR) and multiple congenital anomalies (MCA). The patients were seen at our genetics center (Center for Human Genetics, U.Z.Leuven).

ORGANISM(S): Homo sapiens

SUBMITTER: Joris Vermeesch

PROVIDER: E-GEOD-6538 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

An experimental loop design for the detection of constitutional chromosomal aberrations by array CGH.

Allemeersch Joke J Van Vooren Steven S Hannes Femke F De Moor Bart B Vermeesch Joris Robert JR Moreau Yves Y

BMC bioinformatics 20091119

<h4>Background</h4>Comparative genomic hybridization microarrays for the detection of constitutional chromosomal aberrations is the application of microarray technology coming fastest into routine clinical application. Through genotype-phenotype association, it is also an important technique towards the discovery of disease causing genes and genomewide functional annotation in human. When using a two-channel microarray of genomic DNA probes for array CGH, the basic setup consists in hybridizing ...[more]

PMID: 19925645

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Project description:Research on the ability of certain organisms to reconstruct missing structures of their bodies is still in its infancy, despite numerous efforts performed in multiple species. Using expression profile analyses on different timepoints that cover wound healing and regeneration processes (0, 24 and 72 hours post injury), we studied the regenerative behaviour of fragmented wing imaginal discs of D. melanogaster implanted into adult flies. First, through the comparison between cut and intact discs, we identified the effect of implantation on the regeneration process. Filtering this information, we then constructed the specific early regeneration gene signature of wing discs in which multiple transcription factors, immune response genes and members of the JNK, Notch and WNT signaling pathways seem to play an important role. We next compared the transcriptomes of discs 24 and 72 hours after fragmentation to characterize the regenerative machinery and observed a temporal decrease in the cellular metabolic processes, RNA processing and gene expression machinery, suggesting the discs normal activity was stopped on this first interval of time in response to injury and implantation offences. Based on the expression patterns, we elaborated a catalogue of genes involved in wing disc regeneration divided into four classes (wound healing, regeneration, quick response, constant response). Imaginal discs from third instar larvae were 3/4 fragmented, implanted into the abdomen of adult flies and cultured. In order to subtract the noise due to implantation, we repeated the same protocol using intact discs that were cultivated for 24h. Therefore, a total of 12 microarrays were hybridized: four microarrays (with total RNA from non cut wing discs at 0 and 24 hours) were used to assess the effect of the implantation procedure in intact wing discs and the rest (8) were used to measure changes in gene expression in the first 24 hours after disc dissection and implantation (total RNA from wing discs at 0 and 24 hours was hybridized) and during the period between 24 and 72 hours after the cut (total RNA from wing discs at 24 and 72 hours was hybridized). At least two independent total RNA extractions were carried out (using the RNeasy Protect Mini Kit from Qiagen Inc.) for each condition. The four microarrays hybridized for each pair of conditions were done in biological replicate pairs with dyes swapped to take dye bias into account. The whole set of microarrays was normalized following the same protocol, extracting in each case the list of significant genes (at least 1.5-fold change, FDR adjusted pvalue < 0.05).

Dataset Information

An experimental loop design improves the detection of congenital chromosomal aberrations by array CGH

Publications

An experimental loop design for the detection of constitutional chromosomal aberrations by array CGH.

Similar Datasets

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