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Impact of low copy repeats on the generation of balanced and unbalanced chromosomal aberrations in mental retardation

Item Type:Article
Title:Impact of low copy repeats on the generation of balanced and unbalanced chromosomal aberrations in mental retardation
Creators Name:Erdogan, F. and Chen, W. and Kirchhoff, M. and Kalscheuer, V.M. and Hultschig, C. and Mueller, I. and Schulz, R. and Menzel, C. and Bryndorf, T. and Ropers, H.H. and Ullmann, R.
Abstract:Low copy repeats (LCRs) are stretches of duplicated DNA that are more than 1 kb in size and share a sequence similarity that exceeds 90%. Non-allelic homologous recombination (NAHR) between highly similar LCRs has been implicated in numerous genomic disorders. This study aimed at defining the impact of LCRs on the generation of balanced and unbalanced chromosomal rearrangements in mentally retarded patients. A cohort of 22 patients, preselected for the presence of submicroscopic imbalances, was analysed using submegabase resolution tiling path array CGH and the results were compared with a set of 41 patients with balanced translocations and breakpoints that were mapped to the BAC level by FISH. Our data indicate an accumulation of LCRs at breakpoints of both balanced and unbalanced rearrangements. LCRs with high sequence similarity in both breakpoint regions, suggesting NAHR as the most likely cause of rearrangement, were observed in 6/22 patients with chromosomal imbalances, but not in any of the balanced translocation cases studied. In case of chromosomal imbalances, the likelihood of NAHR seems to be inversely related to the size of the aberration. Our data also suggest the presence of additional mechanisms coinciding with or dependent on the presence of LCRs that may induce an increased instability at these chromosomal sites.
Keywords:Chromosome Aberrations, Bacterial Artificial Chromosomes, Cohort Studies, Computational Biology, Gene Duplication, Human Genome, Fluorescence In Situ Hybridization, Karyotyping, Mental Retardation, Nucleic Acid Hybridization, Genetic Recombination, Genetic Translocation
Source:Cytogenetic and Genome Research
ISSN:1424-8581
Publisher:Karger (Switzerland)
Volume:115
Number:3-4
Page Range:247-253
Date:November 2006
Official Publication:https://doi.org/10.1159/000095921
PubMed:View item in PubMed

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