Prenatal Diagnosis, array CGH and Normal Genomic Imbalances in the Human Genome
Array-based comparative genomic hybridization (aCGH) can be used as a genome-wide assessment of chromosomal imbalances at a high resolution. Indeed, in studies using a 1-Mb resolution aCGH platform on clinically-indicated, postnatal cases (with normal GTG-banded karyotype results), abnormal aCGH results can be observed in as many as 20% of referred cases. Genome-wide aCGH testing in higher risk prenatal cases (e.g. cases with abnormal ultrasound but normal GTG-banded karyotype results), may prove to be similarly useful. However, the recent appreciation of the widespread existence of copy number variation (CNV) in the genomes of healthy, normal individuals will likely complicate interpretation of high resolution, genome-wide aCGH testing in prenatal settings. Hence, comprehensive identification and characterization of CNVs should be made a priority, which would facilitate the common use of this technology for prenatal diagnosis. A summary of recent research developments on CNVs and considerations in prenatal clinical applications will be presented.