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Detection of chromosomal imbalances in children with idiopathic mental retardation by array based comparative genomic hybridisation (array-CGH)
  1. J Schoumans1,
  2. C Ruivenkamp1,
  3. E Holmberg2,
  4. M Kyllerman3,
  5. B-M Anderlid1,
  6. M Nordenskjöld1
  1. 1Department of Molecular Medicine, Karolinska Hospital, CMM L8:02, SE-17176 Stockholm, Sweden
  2. 2Department of Clinical Genetics, Sahlgrenska University Hospital/East, S-41685 Gothenburg, Sweden
  3. 3The Queen Silvia Children’s Hospital, Section of Neuropediatrics, Gothenburg University, Gothenburg, Sweden
  1. Correspondence to:
 Jacqueline Schoumans
 Department of Molecular Medicine, Karolinska Hospital, CMM L8:02, SE-17176 Stockholm, Sweden;


Chromosomal aberrations are a common cause of multiple anomaly syndromes that include growth and developmental delay and dysmorphism. Novel high resolution, whole genome technologies, such as array based comparative genomic hybridisation (array-CGH), improve the detection rate of submicroscopic chromosomal abnormalities allowing re-investigation of cases where conventional cytogenetic techniques, Spectral karyotyping (SKY), and FISH failed to detect abnormalities. We performed a high resolution genome-wide screening for submicroscopic chromosomal rearrangements using array-CGH on 41 children with idiopathic mental retardation (MR) and dysmorphic features. The commercially available microarray from Spectral Genomics contained 2600 BAC clones spaced at approximately 1 Mb intervals across the genome. Standard chromosome analysis (>450 bands per haploid genome) revealed no chromosomal rearrangements. In addition, multi-subtelomeric FISH screening in 30 cases and SKY in 11 patients did not detect any abnormality. Using array-CGH we detected chromosomal imbalances in four patients (9.8%) ranging in size from 2 to 14 Mb. Large scale copy number variations were frequently observed. Array-CGH has become an important tool for the detection of chromosome aberrations and has the potential to identify genes involved in developmental delay and dysmorphism. Moreover, the detection of genomic imbalances of clinical significance will increase knowledge of the human genome by performing genotype-phenotype correlation.

  • array-CGH, array based comparative genomic hybridisation
  • HR-CGH, high resolution comparative genomic hybridisation
  • LCVs, large copy number variants
  • MR, mental retardation
  • SKY, Spectral karyotyping
  • WHS, Wolf Hirshhorn syndrome
  • array-CGH
  • dysmorphism
  • large scale copy number variations
  • mental retardation
  • submicroscopic chromosome aberrations

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  • This work was supported by funds from the Swedish Medical Research Council, Frimurarna Barnahuset Foundation, Linnea och Josef Carlsson Stiftelse, Stiftelsen Sävstaholm, and the Ronald McDonald Child Foundation.

  • Competing interests: none declared