Abstract:A boy, aged 6 months, had the manifestations of intellectual and motor developmental delay, head instability, general weakness, unawareness of grasping objects by hands, and unusual facies (slightly wide eye distance, epicanthus, esotropia, mouth-opening appearance, short philtrum, and low-set ears). Gene detection results showed a de novo heterozygous frameshift mutation of the CHAMP1 gene at the chromosomal location of chr13:115089847, and nuclear acid was changed to c.530delCinsTTT, resulting in a change in amino acid to p.S177Ffs*2. Therefore, the boy was diagnosed with autosomal dominant intellectual disability-40 caused by the mutation in the CHAMP1 gene. This case report suggests that for children with unexplained intellectual disability, especially those with generalized hypotonia and severe language disorder, the possibility of CHAMP1 gene mutation should be considered, and genetic testing should be performed as early as possible.