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

摘要： 收集2019年6月至2020年9月天津市儿童医院康复科收治的3例CTNNB1基因突变致智力障碍患儿临床资料，分析临床及遗传学特点。结果发现，3例患儿均存在认知障碍、运动落后、语言障碍、颅面畸形特征及小头畸形；均有轴向肌张力减低，远端肌张力高；均有行为异常；2例有视觉异常；1例还存在眼球震颤；1例合并肌张力障碍，运动不协调；1例存在惊吓过度；3例均无癫痫；3例目前均未获得独走能力。3例患者CTNNB1基因突变特点为2例移码突变（Exon3 c.82-83del和Exon14 c.2098dupA）和1例无义突变（Exon3 c.198G>A），均为致病性变异，父母均为野生型，均未见既往文献报道，为新突变。由此认为，该病临床表型复杂，主要特点相对典型，为临床早期识别本病提供了依据。其基因突变类型以剪接突变和无义突变为主，该文3例CTNNB1基因突变均为新突变，扩大了疾病基因突变谱。

关键词: CTNNB1基因, 智力障碍, 临床特点