• Rongyue Wang, Tingying Lei, Fang Fu, Ru Li, Xiangyi Jing, Xin Yang, Juan Liu, Dongzhi Li, and Can Liao.
• Southern Medical University, Guangzhou, 510515, Guangdong, China; The Second Hospital affiliated to Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China.
• Pediatr Neonatol. 2019 Feb 1; 60 (1): 35-42.

Background And MethodsChromosome microarray analysis (CMA) is currently the first-tier diagnostic assay for the evaluation of developmental delay (DD) and intellectual disability (ID) with unknown etiology. Here, we present our clinical experience in implementing whole-genome high-resolution single nucleotide polymorphism (SNP) arrays to investigate 489 patients with unexplained DD/ID in whom standard karyotyping analyses showed normal karyotypes. This study aimed to assess the usefulness of CMA for clinical diagnostic testing in the Chinese population.ResultsA total of 489 children were classified into three groups: isolated DD/ID (n = 358), DD/ID with epilepsy (n = 49), and DD/ID with other structural anomalies (n = 82). We identified 126 cases (25.8%, 126/489) of pathogenic copy number variants (CNVs) by CMA, including 89 (24.9%, 89/358) with isolated DD/ID, 13 (26.5%, 13/49) with DD/ID with epilepsy, and 24 (29.3%, 24/82) with DD/ID with other structural anomalies. Among the 126 cases of pathogenic CNVs, 79 cases were identified as microdeletion/microduplication syndromes, among which 76 cases were classified as common syndromes, and 3 cases were classified as rare syndromes, including 15q24 microdeletion syndrome, Xq28 microduplication syndrome and Lowe syndrome. Additionally, there were forty-seven cases of non-syndromic pathogenic CNVs. The ABAT, FTSJ1, DYNC1H1, and SETBP1 genes were identified as DD/ID candidate genes.ConclusionOur findings suggest the necessity of CMA as a routine diagnostic test for unexplained DD/ID in South China.Copyright © 2018. Published by Elsevier B.V.

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