Chromosome analysis is an important diagnostic tool in the identification of causes of mental retardation, developmental delay, and other developmental disabilities. Cytogenetic approaches have revealed the chromosomal basis of a large number of genetic syndromes. The recent use of microarray-based comparative genomic hybridization (array CGH) has accelerated the identification of novel cytogenetic abnormalities. We present the results of array CGH in 8,789 clinical cases submitted for a variety of developmental problems. Of these cases, 6.9% showed clinically relevant abnormalities, 1.2% showed benign copy-number variants (polymorphisms), 2.5% showed recurrent alterations of unclear clinical significance-many of which are likely to be polymorphisms-and 1.4% showed novel alterations of unclear relevance. Although cytogenetic methods, including array CGH, have great potential for identifying novel chromosomal syndromes, this high-resolution analysis may also result in diagnostic challenges imposed on laboratories and clinicians regarding findings of unclear clinical significance. (c) 2007 Wiley-Liss, Inc.
(c) 2007 Wiley-Liss, Inc.