Genetic etiology analysis of 420 children with neurodevelopmental disorders

Objective To investigate the genetic etiology of neurodevelopmental disorders (NDD), and to provide a theoretical basis for its genetic counseling, family risk evaluation and prenatal diagnosis. Methods Karyotype analysis and chromosome microarray analysis (CMA) were conducted of the data from 420 children diagnosed accor-ding to NDD diagnostic criteria at Maternal and Child Health Hospital of Hunan Province from January 2016 to December 2018. Results Among the 420 cases, 14 cases (3.33%, 14/420 cases) with global developmental disabilities/intellectual disabilities (GDD/ID) had chromosomal abnormalities.The location of chromosome breakpoints and the range of deleted or duplicated fragments in 13 cases were further determined by using CMA.In this study, pathogenic copy number variations (CNVs) were detected in 61 children (14.52%, 61/420 cases), which included 31 cases (50.82%, 31/61 cases) of known syndromes, including Angelman/Prader-Will syndrome (8 cases), Williams syndrome (3 cases), Phelan-McDermid syndrome (3 cases) and other 13 syndromes, and 30 cases with clinically significant pathogenic CNVs.Additionally, by the combination of CMA and fluorescence in situ hybridization (FISH), a family were diagnosed with mental retardation caused by 10q26 and 12p13 occult rearrangement. Conclusions Chromosomal abnormalities and genomic microdeletion/duplication are the primary genetic causes for children with NDD.Combination of karyotype analysis, CMA and FISH can provide definite etiological diagnosis for these children, which has important clinical signi-ficance for the treatment of children and guidance of their parents′ reproduction.