Aneuploidy detection in single cells using DNA array-based comparative genomic hybridization

The use of metaphase comparative genomic hybridization (CGH) to screen all human chromosomes for aneuploidy in preimplantation embryos is hindered by the time required to perform the analysis. We report in this paper a novel approach to manufacture a DNA microarray for CGH for the detection of aneuploidy in single cells. We spotted human chromosome-specific libraries on glass slides that were depleted of repetitive sequences and tested our array CGH method in 14 experiments using either single male and/or single female lymphocytes. For the autosomes, the mean normalized ratios were all close to the expected ratio of 1.0 with overall 300/308 (97%) of the normalized ratios falling within the range 0.75 to 1.25. It was possible to deduce the correct copy number of the X chromosome in 13/14 (92.9%) separate array CGH experiments but the Y chromosome in only 4/14 (29%). We tested our microarray CGH method on a single fibroblast from each of three cell lines containing a specific chromosome aneuploidy (trisomy 13, 15 or 18) and in each case our microarray analysis was able to obtain a diagnosis based on the fact that the aneuploid chromosome gave the highest ratio (1.32, 1.27 and 1.27 respectively) with the ratios of all other chromosomes falling within the range 0.75-1.25. Requiring just 30 h, our method may be more suitable for PGD aneuploidy screening than metaphase CGH.