Molecular diagnosis of children with unexplained intellectual disability/ developmental delay by array-CGH

Objective To analyze the potential pathogenic genomic imbalance in children with unexplained intellectual disability(ID) and/or developmental delay(DD) and its association with phenotypes, and to investigate the value of array-based comparative genomic hybridization(array-CGH) in clinical molecular genetic diagnosis.Methods The whole genome of 16 children with ID/DD was scanned by the array-CGH for detection of genomic copy number variations(CNVs), and the revealed genomic imbalance was confirmed by multiplex ligation-dependent probe amplification. Results G-band karyotyping of peripheral blood cells showed no abnormalities in the 16 children. The results of the array-CGH revealed that 6(38%) of the 16 patients had genomic CNVs, and 3 cases of CNVs were normal polymorphic changes; 1 CNV was a microdeletion of 4p16.3, which was the critical region for WolfHirschhorn syndrome, and 1 CNV was a microdeletion of 7q11.23, which was the critical region for Williams-Beuren syndrome. Moreover, a CNV was identified with two duplications at 2q22.2 and 15q21.3 in a boy, which proved to have a clinical significance due to its association with ID, brain DD, unusual facies, cryptorchidism, irregular dentition, etc. Conclusions Array-CGH allows for the etiological diagnosis in some of the children with unexplained ID/DD. As a high-throughput and rapid tool, it has a great clinical significance in the etiological diagnosis of ID/DD.