Copy number variations associated with idiopathic autism identified by whole-genome microarray-based comparative genomic hybridization

Abstract

Objectives: Autism spectrum disorder (ASD) has been thought to have strong genetic background, but major contributing genes or associated molecular-genetic pathways are yet to be identified. To explore the idiopathic ASD-associated copy number variations (CNVs), we conducted case-control study using whole-genome copy number analysis.

Methods: Whole-genome microarray-based comparative genomic hybridization was carried out on 28 children (24 boys and four girls) diagnosed as ASD and 62 Korean adults (45 males and 17 females) without any signs of abnormalities and family history of genetic disorders as normal controls. Fluorescence in-situ hybridization and capillary electrophoresis-single-strand conformational polymorphism were used for quantitative verification of the ASD-associated CNVs.

Results: Thirty-eight CNVs were identified. Among them, the distributions of copy number loss CNVs on 8p23.1 (odds ratio: 5.1, 95% confidence interval: 1.7-14.5, P=0.003) and on 17p11.2 (odds ratio: uncalculable because of zero cell, P=0.008) were found to be significantly different between ASD and control groups. DEFENSIN family occurs in a cluster at 8p23.1 region. Fluorescence in-situ hybridization and capillary electrophoresis-single-strand conformational polymorphism coherently showed reduced copy number of DEFENSIN in cases with 8p23.1 copy number loss CNV, which validated microarray-based comparative genomic hybridization results; but there are no known coding genes in the CNV on 17p11.2.

Conclusion: Our approach as well as results can help to elucidate the genetic mechanism of idiopathic ASD.