Medical applications of array CGH and the transformation of clinical cytogenetics.

Microarray-based comparative genomic hybridization (array CGH) merges molecular diagnostics with traditional chromosome analysis and is transforming the field of cytogenetics. Prospective studies of individuals with developmental delay and dysmorphic features have demonstrated that array CGH has the ability to detect any genomic imbalance including deletions, duplications, aneuploidies and amplifications. Detection rates for chromosome abnormalities with array CGH range from 5-17% in individuals with normal results from prior routine cytogenetic testing. In addition, copy number variants (CNVs) were identified in all studies. These CNVs may include large-scale variation and can confound the diagnostic interpretations. Although cytogeneticists will require additional training and laboratories must become appropriately equipped, array CGH holds the promise of being the initial diagnostic tool in the identification of visible and submicroscopic chromosome abnormalities in mental retardation and other developmental disabilities. Copyright (c) 2006 S. Karger AG, Basel.