Comparative Genomic Hybridization: a companion to conventional cytogenetics

Lisa L.P. SIU and Yok-Lam KW0NG*

From the Department of Pathology, Queen Elizabeth Hospital and the Department of Medicine*, Queen Mary Hospital, Hong Kong.

Comparative genomic hybridization (CGH) is a recently described molecular-cytogenetic technique that globally assays for chromosomal gains and losses throughout the entire genome. Normal metaphase chromosomes are competitively hybridized with two differentially fluorochrome-labeled genomic DNAs (test and reference). Using fluorescence microscopy and digital image analysis, regions of gain or loss of DNA sequences in thc test genome are reflected in the ratio of the intensities of the two fluorochromes along the target chromosomes. CGH has proved to be a valuable tool in tumour genetics. Moreover, the efficacy of CGH in revealing aneuploidies is also a useful adjunct 1n screening for prenatal and neonatal chromosomal aberrations.

Key words: Comparative genomic hybridization. Cytogenetics. Tumour genetic. Aneuploid

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