Sample interview questions: Can you explain the process of performing array-based comparative genomic hybridization (aCGH) for detecting genomic imbalances?
Sample answer:
Array-Based Comparative Genomic Hybridization (aCGH)
aCGH is a robust and high-throughput method used to detect genomic imbalances by comparing the DNA copy number of a test sample to a reference sample.
Procedure:
- DNA Extraction and Labeling:
- High-quality DNA is extracted from the test and reference samples.
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The test sample DNA is labeled with a fluorescent dye (e.g., Cy3), while the reference sample DNA is labeled with a different dye (e.g., Cy5).
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Array Hybridization:
- The labeled DNA samples are mixed and hybridized to an array containing thousands of DNA probes.
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These probes are specific for different genomic regions.
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Fluorescence Scanning and Signal Detection:
- The array is scanned using a fluorescence scanner to detect the signals from the two dyes.
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The signal intensities are quantified, providing information on the relative copy number of each probe.
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Data Analysis:
- The signal intensities are normalized and compared between the test and reference samples.