Nicoletta Villa and Angela Bentivegna contributed equally to this work.
Article first published online: 13 MAY 2011
Copyright © 2011 Wiley-Liss, Inc.
American Journal of Medical Genetics Part A
Volume 155, Issue 6, pages 1425–1431, June 2011
How to Cite
Villa, N., Bentivegna, A., Ertel, A., Redaelli, S., Colombo, C., Nacinovich, R., Broggi, F., Lissoni, S., Bungaro, S., Addya, S., Fortina, P. and Dalprà, L. (2011), A de novo supernumerary genomic discontinuous ring chromosome 21 in a child with mild intellectual disability. Am. J. Med. Genet., 155: 1425–1431. doi: 10.1002/ajmg.a.34010
How to Cite this Article: Villa N, Bentivegna A, Ertel A, Redaelli S, Colombo C, Nacinovich R, Broggi F, Lissoni S, Bungaro S, Addya S, Fortina P, Dalprà L. 2011. A de novo supernumerary genomic discontinuous ring chromosome 21 in a child with mild intellectual disability. Am J Med Genet Part A 155:1425–1431.
- Issue published online: 20 MAY 2011
- Article first published online: 13 MAY 2011
- Manuscript Accepted: 17 FEB 2011
- Manuscript Received: 12 NOV 2010
- Fondazione Cariplo
- ring chromosome 21;
- fluorescence in situ hybridization (FISH);
Small supernumerary marker chromosomes (sSMCs) are structurally abnormal extra chromosomes that cannot be unambiguously identified or characterized by conventional banding techniques alone, and they are generally equal in size or smaller than chromosome 20 of the same metaphase spread. Small supernumerary ring chromosomes (sSRCs), a smaller class of marker chromosomes, comprise about 10% of the cases. For various reasons these marker chromosomes have been the most difficult to characterize; although specific syndromes have not yet been defined, 60% of cases are associated with an abnormal phenotype. The chromosomal material involved, the degree and tissutal distribution of mosaicism, and the possible presence of uniparental disomy, are the important factors determining whether or not the ring chromosome will give rise to symptoms. Using conventional and molecular cytogenetics approaches we identified a de novo chromosome 21 sSRC in a child with speech delay and mild intellectual disability. By using aCGH analysis and SNP arrays, we report the presence of two discontinuous regions of chromosome 21 and the paternal origin of the sSRC. A thorough neuropsychiatric evaluation is also provided. Only few other cases of complex discontinuous ring chromosomes have been described in detail. © 2011 Wiley-Liss, Inc.