关键词: CTNNB1基因, 智力障碍, 临床特点

Abstract: The clinical data of 3 cases of mental retardatiion coused by CTNNB1 gene mutation who were treated in Tianjin Chilclren’s Hospital from june 2019 to saptember 2020 were collected，their clinical and genetic characteristics were analyzed，and the clinical and gene mutation characteristics of the patients reported at home and abroad were summarized. All the 3 patients had cognitive impairment，motor retardation，speech impairment，craniofacial malformation and microcephaly.Axial muscle tone was decreased and distal muscle tone was high. All had abnormal behaviors；2 cases had visual abnormalities；one case also had nystagmus；1 case was with dystonia and uncoordinated movement. Hyperstartle was found in 1 case. None of the 3 cases had epilepsy. None of them had the ability to walk alone at present.The mutation characteristics of CTNNB1 gene in the 3 cases were trunk-coding mutation in 2 cases（Exon3 c.82-83del and Exon14 c.2098DupA）and nonsense mutation in 1 case（Exon3 c.198G >A），all of which were pathogenic mutations，and the parents were all wild-type，none of which had been reported in previous literature，and they were new mutations. It is therefore believed that the clinical phenotype of this disease is complicated，but its main characteristics are relatively typical，which provides the basis for early clinical recognition of this disease. Splicing and nonsense mutations are the main mutation types in CTNNB1 gene.In this study，CTNNB1 gene mutations in 3 cases are all new mutations，which expands the gene mutation spectrum of this disease.

Key words: CTNNB1 gene, mental retardation, clinical characteristics