2.1 Study participants
Study participants were recruited from 10 hospitals located in China from February 2018 to August 2020. Participants meeting the following inclusion criteria were enrolled: (i) less than 18 years of age with a clinical diagnosis of GDD/ID, (ii) brain MRI results available and accessible; (iii) normal karyotype, (iv) clinical and phenotypic information available (v) inconclusive results from at least one previous genomic test (CMA or ES), and (vi) raw data from CMA and/or ES available for reanalysis. The exclusion criteria were the following: (i) GDD/ID was determined to be caused by non-genetic factors (e.g., infection, trauma) and (ii) The patient was diagnosed by previous reanalysis.
Written consent was obtained for all patients. The Ethics Board of Xin Hua Hospital reviewed and approved the study protocol (XHEC-C-2018-002). The study adheres to the principles set out in the Declaration of Helsinki. Written consent was obtained for all patients. The study protocol was submitted to ClinicalTrials under the accession No: NCT03424772.