Genomic characterization of some Iranian children with idiopathic mental retardation using array comparative genomic hybridization.
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.


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.


CONCLUSIONS
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.
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Farkhondeh
F
Behjati
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Saghar Ghasemi
SG
Firouzabadi
Kariminejad and Najmabadi Pathology and Genetics Center, Tehran, Iran.
Roxana
R
Kariminejad
Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Roshanak
R
Vameghi
Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Firouzeh
F
Sajedi
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran ; Department of Medical Genetics and Sarem Cell Research Center, Sarem Womens' Hospital, Iran.
Yousef
Y
Shafaghati
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Behruz Ebrahimizade
BE
Ghasemlou
Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Azadeh
A
Shojaei
Shahroud Welfare Organization, Shahroud, Iran.
Peyman
P
Jamali
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Ideh
I
Bahman
Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
Hossein
H
Najmabadi
Array comparative genomic hybridization; chromosome abnormality; dysmorphism; genomic variation; idiopathic mental retardation