Abstract: Objective To investigate the clinical symptoms and gene variation of XiaGibbs syndrome(XGS) caused by ADHC1 gene mutation. Methods The clinical data of 2 children with XGS caused by the ADHC1 gene mutation and the results of whole exome sequencing(WES) were analyzed and summarized retrospectively. The literatures were reviewed to collect XGS cases with confirmed genetic diagnosis, and the clinical phenotypes and gene mutation features were summarized. Results The male patient was 7 months and the female patient was 7 years and 11 months. Both patients had sport language retardation, muscle tension reduction, and brain MRI and EEG abnormalities. The male patient had an special facial features(binocular esotropia, low bridge of nose), skin hemangioma, patent foramen ovale, new nonsense mutation of ADHC1 gene found by WES［1-8c.4321(exon) C > T(p.Q1441X,163)］. The female had epilepsy, new frame shift mutation of ADHC1 gene found by WES［c.1122dupC (p.gly375fs)］.Eight English literatures and two Chinese literatures were retrieved from the Pubmed, Wanfang and CNKI databases. There were 40 cases of AHDC1 mutation in total including the 2 cases. Most of them had comprehensive underdevelopment(97.5%), hypotonia(87.5%), special facial features(77.5%), and sleep apnea(42.5%). Dysgenesis of corpus callosum was common in craniocerebral imaging, and frame shift mutation(70%) was the most common gene mutation. Conclusion The main symptoms of XGS caused by AHDC1 gene mutation are underdevelopment, hypotonia, special facial features and sleep apnea, which can be diagnosed by gene detection based on clinical phenotypes.

Key words: XiaGibbs syndrome, AHDC1, Gene, Child