The cytogenetic view of standard comparative genomic hybridization (CGH): Deletions of 20q in human leukemia as a measure of the sensitivity of the technique

Background: The limits of the resolving power of comparative genomic hybrid ization (CGH) have been given as 10-20 Mbp if at least 50 % of the studied neoplastic cell population carried the corresponding aberration. Material a nd Methods: Genomic DNA Of five cases of hematologic neoplasias, in all of which - among other anomalies -deletions of different size Of chromosome 20 q were found by GTG banding and confirmed by FISH analyses, was subjected t o CCH. Results: CGH revealed four types of del(20q), and, in addition, dete cted a tiny terminal del(3p) in one of the cases. The size of the smallest deleted segment, clearly visible by eye on the CGH metaphase image, was est imated to range between 5 and 7 Mbp. Conclusion: Visual determination was s hown to have a stronger resolving power in CGH than software used for the a nalysis in one case, while in another one, the I results obtained from the ratio profiles would have been consider ed insignificant without the knowle dge of the hyblidization pattern on the corresponding CGH metaphase images. The potential of the standard CGU technique nor only to detect bur visuali ze small segmental aneusomies as well, suggests that its resolution actuall y mirrors the resolution of banding techniques.