Objective: To probe into the pathogenic genes of sick sinus syndrome (SSS) through whole-exon sequencing (WES)

and to investigate the correlation between gene mutation type and clinical phenotype. Methods: Clinical data of a patient with SSS and the family members in Shanghai Children’s Hospital were collected. Peripheral blood from the patient and family members was collected

and blood DNA was extracted. WES was used to search for pathogenic genes

Sanger sequencing was used to verify possible pathogenic gene mutations

and pathogenicity prediction software was used to predict the correlation between genotype and phenotype. Results: Compared with unaffected individuals and multiple biological databases

a heterozygous mutation of SCN5A gene c.999-1G>A was found

and it was a possible causative gene in SSS. This mutation was reported for the first time in Han children. Conclusion: The mutation of SCN5A gene c.999-1G>A is the pathogenic site of sporadic SSS. Through the study of SSS related pathogenic genes

it is of great clinical significance for clinicians to accurately judge such patients and carry out biological cardiac pacing therapy as early as possible in the future.