Abstract:

To create a useful comparative genomic hybridization (CGH) for prenatal diagnosis. Methods5 pregnancies with abnormal cytogenetic results and 11 pregnancies with malformed infants were enrolled in this study. Sample DNA and control DNA were labeled with Spectrum Green dUTP and SpectrumRed dUTP respectively using the nick translation kit. Simultaneously, fluorochromeexchanged CGH was designed. Sample DNA was labeled with SpectrumRed dUTP and genomic DNA was labeled with SpectrumGreen. The karyotyping was performed based on the DAPI banding pattern. A fluorescence intensity ratio (FR) profile was calculated after background correction and normalization of the green to red ratio for each metaphase to 1.0. Trisomies or partial chromosome gains were defined as FR＞1.25. Monosomies or partial chromosome losses were defined as FR＜0.75. ResultsEach sample was successfully analyzed for chromosomal abnormalities by CGH comparing with conventional cytogenetic analyses. Karyotype of a stillborn fetus was Del (4)q32qter by CGH, while only 4q distal losses were identified by conventional cytogenetic analyses. ConclusionsExchanging labeled fluorochrome can reduce inconsistencies in the results caused by deviations in the process of DNA labeling and hybridization, and can be a useful and necessary supplement for conventional cytogenetic analysis.

Key words: Comparative genomic hybridization; Chromosomal; Prenatal diagnosis