• Yanjie Fan, Yanming Wu, Lili Wang, Yu Wang, Zhuwen Gong, Wenjuan Qiu, Jingmin Wang, Huiwen Zhang, Xing Ji, Jun Ye, Lianshu Han, Xingming Jin, Yongnian Shen, Fei Li, Bing Xiao, Lili Liang, Xia Zhang, Xiaomin Liu, Xuefan Gu, and Yongguo Yu.
• Department of Pediatric Endocrinology/Genetics, Xinhua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, 1665 Kongjiang Road, Shanghai, 200092, China.
• Bmc Med Genomics. 2018 May 24; 11 (1): 49.

BackgroundDevelopmental delay (DD) and intellectual disability (ID) are frequently associated with a broad spectrum of additional phenotypes. Chromosomal microarray analysis (CMA) has been recommended as a first-tier test for DD/ID in general, whereas the diagnostic yield differs significantly among DD/ID patients with different comorbid conditions.MethodsTo investigate the genotype-phenotype correlation, we examined the characteristics of identified pathogenic copy number variations (pCNVs) and compared the diagnostic yields among patient subgroups with different co-occurring conditions.ResultsThis study is a retrospective review of CMA results generated from a mixed cohort of 710 Chinese patients with DD/ID. A total of 247 pCNVs were identified in 201 patients (28%). A large portion of these pCNVs were copy number losses, and the size of copy number losses was generally smaller than gains. The diagnostic yields were significantly higher in subgroups with co-occurring congenital heart defects (55%), facial dysmorphism (39%), microcephaly (34%) or hypotonia (35%), whereas co-occurring conditions of skeletal malformation (26%), brain malformation (24%) or epilepsy (24%) did not alter the yield. In addition, the diagnostic yield nominally correlated with ID severity.ConclusionVaried yields exist in DD/ID patients with different phenotypic presentation. The presence of comorbid conditions can be among factors to consider when planning CMA.

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