Abstract: 　Objective　To explore the clinical characteristics of epilepsy with cognitive development disorder caused by SYNGAP1 gene mutation in children. Methods　The clinical data of three children with SYNGAP1 mutation revealed by secondgeneration sequencing from 2017 to 2019 were collected and analyzed retrospectively. Results　There were three cases (2 boys and 1 girl), all of them had onset in childhood. Their epileptic attacks were eyelid myoclonia with absence, myoclonic atonic and focal seizure, respectively. All of the three children had cognitive abnormalities, one of them had stereotyped, aggressive behavior, lacking of eye contact and social interaction. No convulsion or developmental disorder was found in their parents and other family members. Three children all had de novo heterozygous mutations in SYNGAP1 gene with autosomal dominant inheritance. The variations include c.623delC (p.P208Qfs*15) in exon 6, c.67+1G＞A (splicing) in exon 1 and c.2158G＞A (p.Asp720Asn) in exon 13, respectively, among which the missense mutation in exon 13 caused focal seizure. Conclusion　SYNGAP1 gene mutation can lead to epilepsy with cognitive developmental disorders, and epileptic seizures has clinical diversity.

Key words: epilepsy;　developmental disorder;　SYNGAP1 gene;　mutation