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Genomic characterization of some Iranian children with idiopathic mental retardation using array comparative genomic hybridization
Farkhondeh Behjati1, Saghar Ghasemi Firouzabadi1, Roxana Kariminejad2, Roshanak Vameghi3, Firouzeh Sajedi3, Yousef Shafaghati4, Behruz Ebrahimizade Ghasemlou1, Azadeh Shojaei5, Peyman Jamali6, Ideh Bahman1, Hossein Najmabadi1
1 Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
2 Kariminejad and Najmabadi Pathology and Genetics Center, Tehran, Iran
3 Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
4 Genetics Research Center, University of Social Welfare and Rehabilitation Sciences; Department of Medical Genetics and Sarem Cell Research Center, Sarem Womens' Hospital, Iran
5 Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
6 Shahroud Welfare Organization, Shahroud, Iran
Correspondence Address:
Farkhondeh Behjati
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran
Iran
 Source of Support: This work is funded through a grant by the deputy of
research of University of Social Welfare and Rehabilitation Sciences, Conflict of Interest: None
DOI: 10.4103/0971-6866.124373
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Background: Mental retardation (MR) has a prevalence of 1-3% and genetic causes are present in more than 50% of patients. Chromosomal abnormalities are one of the most common genetic causes of MR and are responsible for 4-28% of mental retardation. However, the smallest loss or gain of material visible by standard cytogenetic is about 4 Mb and for smaller abnormalities, molecular cytogenetic techniques such as array comparative genomic hybridization (array CGH) should be used. It has been shown that 15-25% of idiopathic MR (IMR) has submicroscopic rearrangements detectable by array CGH. In this project, the genomic abnormalities were investigated in 32 MR patients using this technique.
Materials and Methods: Patients with IMR with dysmorphism were investigated in this study. Karyotype analysis, fragile X and metabolic tests were first carried out on the patients. The copy number variation was then assessed in a total of 32 patients with normal results for the mentioned tests using whole genome oligo array CGH. Multiple ligation probe amplification was carried out as a confirmation test.
Results: In total, 19% of the patients showed genomic abnormalities. This is reduced to 12.5% once the two patients with abnormal karyotypes (upon re-evaluation) are removed.
Conclusion: The array CGH technique increased the detection rate of genomic imbalances in our patients by 12.5%. It is an accurate and reliable method for the determination of genomic imbalances in patients with IMR and dysmorphism. |
