Objective　To explore the clinical features and pathogenic genes of sialidosis. Methods　The clinical data and genetic test results of a family with sialidosis were retrospectively analysed. Results　The proband was a 13-year-old girl who presented with limb pain at age 7, followed by progressive vision loss and convulsive seizure. In addition, she also had the sign of ataxia. Fundus examination showed optic atrophy in her eyes. Visual evoked potential showed that the latency of binocular P100 was significantly prolonged. The elder brother of the proband showed similar manifestation. PCR was used to amplify the exons and exon-intron boundaries of the NEU1 gene, and DNA direct sequencing was used to detect the mutation in this gene. It was found that both proband and her brother carried two known pathogenic heterozygous mutations in the NEU1 gene, c.239C>T (p.P80L) and c.544A>G (p.P80L) respectively from both their mother and father of normal phenotype. Conclusion　The causative mutation of the NEU1 gene in the family of sialidosis has been defined.