Project description: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).
Project description:Abnormalities in DNA copy number are frequently found in patients with multiple anomaly syndromes and mental retardation. Array-CGH is a high resolution whole-genome technology which improves detection of submicroscopic aberrations underlying these syndromes. Eight patients with mental disability, multiple congenital anomalies and dysmorphic features were screened for submicroscopic chromosomal imbalances using the GenoSensor Array 300 Chip. Subtelomeric aberrations previously detected by FISH analysis were confirmed in two patients, and accurate diagnosis was provided in two previously undiagnosed complex cases. Microdeletions at 15q11.2-q13 in a newborn with hypotonia, cryptorchidsm and hypopigmentation were detected with few discrepancies between the array results and FISH analysis. Contiguous microdeletion of GSCL, HIRA and TBX1 genes at 22q11.2 was identified in a previously undiagnosed boy with an unusual presentation of the VCF/DiGeorge spectrum. In a newborn with aniridia, a borderline false negative WT1 deletion was observed, most probably because of differences between the size of the genomic deletion and the microarray probe. A false positive rate of 0.2% was calculated for clone-by-clone analysis, while the per patient false positive rate was 20%. Array-based CGH is a powerful tool for the rapid and accurate detection of genetic disorders associated with copy number abnormalities, and can significantly improve clinical genetic diagnosis and care. Keywords: comparative genome hybridization (CGH)
Project description: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 “normal” 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
Project description:Genomic DNA from sporadic breast tumours was isolated and analysed using array CGH. The NKI 1MB BAC/PAC micro array was used to identify chromosomal aberrations of all tumours. Keywords: sporadic breast tumour, CGH
Project description:An ovarian cancer cell line study to identify possible trends between chromosomal aberrations depicted from CGH microarray profiling with expression profiling. CGH microarray profiles of a panel of ovarian cancer cell lines will be analysed and 10 cell lines with chromosomal aberrations of recurrent regions (with the strongest trend) will be taken forward for further expression array analysis to identify candidate genes. CGH microarray analyses will restrict the regions of aberrations with high resolution and accurracy, combined with expression array analysis to pinpoint candidate genes that will relate to the amplified and deleted regions. Identified candidates will allow the better understanding of mechanisms and specific pathways involved in ovarian cancer development.
Project description:Genomic DNA from sporadic breast tumours was isolated and analysed using array CGH. The NKI 1MB BAC/PAC micro array was used to identify chromosomal aberrations of all tumours. Other profiles are located at: GSE9114 Keywords: sporadic breast tumour, CGH.
Project description:In this study, we extend array CGH technology by making the accurate detection of chromosomal imbalances possible from a single fibroblast and blastomere following Phi29 DNA polymerase amplification. Keywords: CGH
Project description:This series represents the data set described in the publication “Impact of low copy repeats on the generation of balanced and unbalanced chromosomal aberrations in mental retardation” by Erdogan et al. (Cytogenetics and Genome Research, accepted). Keywords: array CGH