How to cite this article: Ballif BC, Rorem EA, Sundin K, Lincicum M, Gaskin S, Coppinger J, Kashork CD, Shaffer LG, Bejjani BA. 2006. Detection of low-level mosaicism by array CGH in routine diagnostic specimens. Am J Med Genet Part A 140A:2757–2767.
Detection of low-level mosaicism by array CGH in routine diagnostic specimens†
Article first published online: 13 NOV 2006
Copyright © 2006 Wiley-Liss, Inc.
American Journal of Medical Genetics Part A
Volume 140A, Issue 24, pages 2757–2767, 15 December 2006
How to Cite
Ballif, B. C., Rorem, E. A., Sundin, K., Lincicum, M., Gaskin, S., Coppinger, J., Kashork, C. D., Shaffer, L. G. and Bejjani, B. A. (2006), Detection of low-level mosaicism by array CGH in routine diagnostic specimens. Am. J. Med. Genet., 140A: 2757–2767. doi: 10.1002/ajmg.a.31539
- Issue published online: 21 NOV 2006
- Article first published online: 13 NOV 2006
- Manuscript Accepted: 19 SEP 2006
- Manuscript Received: 30 MAY 2006
- array CGH;
- clinical diagnostics;
- PHA-stimulated cells;
- Pallister–Killian syndrome;
- isochromosome 12p
The advent of microarray-based comparative genomic hybridization (array CGH) promises to revolutionize clinical cytogenetics because of its ability to rapidly screen the genome at an unprecedented resolution. Yet, the ability of array CGH to detect and evaluate low-level mosaicism is not known. Our laboratory has analyzed over 3,600 clinical cases with the SignatureChip® which we developed for the detection of microdeletions, microduplications, aneuploidy, unbalanced translocations, and subtelomeric and pericentromeric copy number alterations. Here, we report 18 cases of mosaicism detected by array CGH in a routine diagnostic setting, 14 of which were not known to us at the time of the analysis. These 14 cases represent ∼8% of all abnormal cases identified in our laboratory. For each case, fluorescence in situ hybridization (FISH) analysis was performed on PHA-stimulated cultures after mosaic chromosome abnormalities were suspected by array CGH. In all cases, FISH confirmed the mosaic chromosome abnormalities which included a variety of marker chromosomes, autosomal trisomies, terminal and interstitial deletions, and derivative chromosomes. Interestingly, confirmatory FISH analyses on direct blood smears indicated that the percentage of abnormal cells in unstimulated cultures was in some cases different than that found in PHA-stimulated cells. We also report the detection of a previously unsuspected case of an isochromosome 12p (associated with Pallister–Killian syndrome) by array CGH using genomic DNA extracted from peripheral blood. These results support a growing body of data that suggests that stimulated peripheral blood cultures likely distort the percentage of abnormal cells and may, for some chromosome abnormalities, make their detection unlikely by conventional analysis. Thus, array CGH, which is based on genomic DNA extracted directly from uncultured peripheral blood, may be more likely to detect low-level mosaicism for unbalanced chromosome abnormalities than traditional cytogenetic techniques. © 2006 Wiley-Liss, Inc.