Compound heterozygous mutations in the neuraminidase 1 gene in type 1 sialidosis: A case report and review of literature

BACKGROUND Type 1 sialidosis,also known as cherry-red spot-myoclonus syndrome,is a rare autosomal recessive lysosomal storage disorder presenting in the second decade of life.The most common symptoms are myoclonus,ataxia and seizure.It is rarely encountered in the Chinese mainland.CASE SUMMARY A 22-year-old male presented with complaints of progressive myoclonus,ataxia and slurred speech,without visual symptoms;the presenting symptoms began at the age of 15-year-old.Whole exome sequencing revealed two pathogenic heterozygous missense variants[c.239C>T(p.P80L)and c.544A>G(p.S182G)in the neuraminidase 1(NEU1)gene],both of which have been identified previously in Asian patients with type 1 sialidosis.All three patients identified in China's Mainland come from three unrelated families,but all three show the NEU1 mutations p.S182G and p.P80L pathogenic variants.Increasing sialidase activity through chaperones is a promising therapeutic target in sialidosis.CONCLUSION Through retrospective analysis and summarizing the clinical and genetic characteristics of type 1 sialidosis,we hope to raise awareness of lysosomal storage disorders among clinicians and minimize the delay in diagnosis.