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Microarray based comparative genomic hybridisation (array-CGH) detects submicroscopic chromosomal deletions and
C Shaw-Smith1, R Redon, L Rickman
1University of Cambridge Department of Medical Genetics, Addenbrooke's Hospital, Hills Road, Cambridge, UK.
Journal of Medical Genetics
|April 3, 2004
Summary
Array comparative genomic hybridization (array-CGH) identified copy number abnormalities in 24% of patients with learning disability and dysmorphic features. This method detects subtle DNA changes missed by routine karyotyping, aiding in diagnosing genetic disorders.
Area of Science:
- Genetics
- Developmental Biology
- Medical Diagnostics
Background:
- Learning disability and dysmorphic features often have unidentified genetic causes.
- Routine karyotyping has limitations in detecting subtle chromosomal abnormalities (e.g., <5 Mb).
Purpose of the Study:
- To investigate subtle DNA copy number changes in patients with learning disability and dysmorphism using array-CGH.
- To evaluate the diagnostic yield of array-CGH for detecting submicroscopic chromosomal rearrangements.
Main Methods:
- Array comparative genomic hybridization (array-CGH) was performed on 50 patients.
- A DNA microarray with large insert clones spaced approximately 1 Mb apart was utilized.
- Analysis focused on identifying copy number variations (deletions and duplications).
Main Results:
- Twelve copy number abnormalities were detected in 12 patients (24% diagnostic yield).
- Seven deletions and five duplications were identified, ranging from single-clone to 14 Mb regions.
- No recurrent deletion or duplication patterns were observed in this cohort.
Conclusions:
- Array-CGH is a sensitive method for detecting submicroscopic chromosomal imbalances in patients with learning disability and dysmorphism.
- This technique significantly increases the diagnostic rate compared to conventional karyotyping.
- Array-CGH is expected to become a standard genome-wide screening tool for such genetic conditions.