Objective: To analyze the clinical phenotype and mutation site in a case of DES gene mutation characterized by cardiac involvement. Methods: The clinical data of a child with severe arrhythmia and cardiomyopathy and the family members were collected

the whole exome sequencing (WES) showed that there was a c.1360C>T mutation in DES gene and was characterized by severe arrhythmia and cardiomyopathy. Peripheral blood of the family was collected and Sanger sequencing was performed to identify the possible pathogenic gene mutations

and the harmfulness of the mutations was predicted through bioinformatics analysis. Results: WES results were confirmed by Sanger sequencing. The child had heterozygous mutation at this site

but the parents did not carry the mutation

which was a de novo mutation. The mutation of DES 454 resulted in a highly conserved arginine mutation to tryptophan in different species

and the prediction software suggested that the mutation was harmful. Based on the analysis of phenotype

the child had large atria and reduced left ventricular ejection fraction

and then received permanent cardiac pacemaker implantation. The abnormal cardiac function was probably induced by the mutation of DES gene. This mutation was first reported in China. Conclusion: The mutation of DES c.1360C>T is probably the pathogenic mutation of children. Mutations in DES gene usually lead to the severe cardiac phenotype

higher fatality rate and poor prognosis.