Comparative genomic hybridization on single cells

Comparative genomic hybridization (CGH) is a molecular cytogenetic technique developed for the analysis of chromosome imbalance in tumors and constitutional chromosome abnormalities. It is based on the analysis of genomic DNA and has the advantage over conventional karyotyping in that it does not require that metaphase chromosomes be obtained from the test material. The application of CGH to single cells requires whole-genome amplification of the DNA to provide sufficient DNA for use as a test sample. This approach has been used successfully to identify aneuploidy in single fibroblasts, amniocytes, and buccal cells that were known to be trisomic. CGH can also identify chromosome errors in single blastomeres from early embryos and in first polar bodies. We have analyzed biopsied blastomeres from embryos conceived by in vitro fertilization using CGH in a clinical preimplantation diagnostic program in which euploid embryos are selected for transfer. This has resulted in established pregnancies in patients with recurrent implantation failure.