Copy number variation and autism: New insights and clinical implications

Genomic research can lead to discoveries of copy number variations (CNVs) which can be a susceptibility factor for autism spectrum disorder (ASD). The clinical translation is that this can improve the care of children with ASD. Chromosome microarray is now the first-tiered genetic investigation for ASD, with a detection rate exceeding conventional cytogenetics and any single gene testing. However, interpretation of the results is challenging and there is no consensus on “what” and “how much” to disclose. In this article, we will review how CNV studies have improved our understanding of ASD, the clinical applications, and related counseling issues. Future direction of autism genetic research is also discussed

Use of clinical chromosomal microarray in Chinese patients with autism spectrum disorder—implications of a copy number variation involving DPP10

Abstract Background Array comparative genomic hybridization (aCGH) is recommended as a first-tier genetic test for children with autism spectrum disorder (ASD). However, interpretation of results can often be challenging partly due to the fact that copy number variants (CNVs) in non-European ASD patients are not well studied. To address this literature gap, we report the CNV findings in a cohort of Chinese children with ASD. Methods DNA samples were obtained from 258 Chinese ASD patients recruited from a child assessment center between January 2011 and August 2014. aCGH was performed using NimbleGen-CGX-135k or Agilent-CGX 60k oligonucleotide array. Results were classified based on existing guidelines and literature. Results Ten pathogenic CNVs and one likely pathogenic CNV were found in nine patients, with an overall diagnostic yield of 3.5%. A 138 kb duplication involving 3′ exons of DPP10 (arr[GRCh37] 2q14.1(116534689_116672358)x3), reported to be associated with ASD, was identified in one patient (0.39%). The same CNV was reported as variant of uncertain significance (VUS) in DECIPHER database. Multiple individuals of typical development carrying a similar duplication were identified among our ancestry-matched control with a frequency of 6/653 (0.92%) as well as from literature and genomic databases. Conclusions The DPP10 duplication is likely a benign CNV polymorphism enriched in Southern Chinese with a population frequency of ~1%. This highlights the importance of using ancestry-matched controls in interpretation of aCGH findings