Comparative Genomic Hybridization to Detect Unbalanced Chromosomal Rearrangement

Comparative genomic hybridization (CGH) is a technique used to detect unbalanced chromosome rearrangements based on the use o f in situ hybridization of differentially labeled DNA. This technique can be used to analyze complex clinical cases which have constitutional chromosomal abnormalities that do not lend themselves to routine chromosomal analysis. CGH was examined in order to develop a reliable and reproducible protocol that can be used as an additional diagnostic tool in Shodair Hospital’s clinical lab. CGH involves the isolation o f both test and reference DNA and the differentially labeling o f the different DNA with fluorescent probes. Then those samples o f DNA were hybridized onto a normal metaphase spread. The slide was examined under a fluorescent microscope and analyzed using Perceptive Scientific Instrument’s MacProbe fluorescent imaging software. It appears that a slightly modified version o f the published Vysis Protocol (1998) yields the best CGH results in our clinical diagnostic genetics laboratory.