How to cite this article: Gruchy N, Lebrun M, Herlicoviez M, Alliet J, Gourdier D, Kottler M-L, Mittre H, Leporrier N. 2008. Supernumerary marker chromosomes management in prenatal diagnosis. Am J Med Genet Part A.
Supernumerary marker chromosomes management in prenatal diagnosis†
Version of Record online: 16 OCT 2008
Copyright © 2008 Wiley-Liss, Inc.
American Journal of Medical Genetics Part A
Volume 146A, Issue 21, pages 2770–2776, 1 November 2008
How to Cite
Gruchy, N., Lebrun, M., Herlicoviez, M., Alliet, J., Gourdier, D., Kottler, M.-L., Mittre, H. and Leporrier, N. (2008), Supernumerary marker chromosomes management in prenatal diagnosis. Am. J. Med. Genet., 146A: 2770–2776. doi: 10.1002/ajmg.a.32532
- Issue online: 24 OCT 2008
- Version of Record online: 16 OCT 2008
- Manuscript Accepted: 13 JUL 2008
- Manuscript Received: 8 FEB 2008
- supernumerary marker chromosomes;
- prenatal diagnosis;
- genetic counseling
To assess the practical usefulness of array-comparative genomic hybridization (a-CGH) when supernumerary marker chromosomes (SMCs) are detected during prenatal diagnosis, we retrospectively studied SMC management in our laboratory before a-CGH availability. In this 11-year study, SMCs were observed in 20/16,810 routine karyotypes (0.12%). Their chromosomal origin, ascertained in 13 cases, remained elusive in seven using conventional cytogenetics and FISH. In the literature, most of SMCs (2/3) are easily identified through conventional cytogenetics and targeted FISH, and in these cases a-CGH would have been unneeded. This technique would have been less helpful in nine cases, that is, bisatellited SMC, isochromosomes and translocation derivatives. On the other hand, a-CGH would have been helpful for the 11 remaining cases. It would have improved diagnostic accuracy of six SMC whom chromosomal origin was ascertained by cytogenetics and FISH and for which prognosis was only based on literature and ultrasonographic data. Among five unidentified SMCs, a-CGH would have been more reassuring for four heterochromatic SMCs than normal ultrasonography alone and would have characterized the unidentified case associated with malformations that was interrupted. However potential pitfalls should be outlined. Using high level resolution chip expose to polymorphism detection and misinterpretation, a very sensitive problem in prenatal diagnosis. Moreover, low grade mosaicism could remain undetectable with this technique, leading to erroneous conclusions. Wisest use of a-CGH should be a complementary approach in prenatal management of SMC. It is specifically appropriate when SMC interpretation remains equivocal and only indirectly based on mode of inheritance, literature data and ultrasonography. © 2008 Wiley-Liss, Inc.