Objective To seek related genetic pathogenic factors by screening for genome-wide copy number variations (CNVs) in 55 Chinese children with unexplained mental retardation or developmental delay (MR/DD) using high resolution array-comparative genomic hybridization (aCGH), identify rare CNVs (microdeletions/duplications) which may associate with MR/DD, and evaluate the effectiveness of aCGH in clinical molecular diagnosis of children with unexplained MR/DD. Methods A total of 55 children with unexplained MR/DD were recruited for this study from June to December in 2013 in SUN Yat-sen Memorial Hospital.Their genomic CNVs were detected by using 25~50 K CytoScan HD chip, then the pathogenic CNVs were analyzed with bioinformatics tools. Results Rare CNVs were identified on 21 out of 55 children with unexplained MR/DD, which had been analyzed with the references from database of genomic variants and were considered as pathogenic CNVs.19 CNVs were related to MR/DD while the other 2 were associated with known syndromes. Conclusions Microdeletions/microduplications related to the genomic CNVs, which couldn't be identified using traditional chromosome analysis, are demonstrated as one of the cause of unexplained MR/DD.aCGH could help with the clinical molecular diagnosis and prognosis of children with unexplained MR/DD, and with the evaluation of the risk of family-recurrence.
Key words
array-comparative genomic hybridization /
mental retardation /
developmental delay /
copy number variations
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