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

Abstract

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 Mainland China 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.

Keywords: Sialidosis; Myoclonus; Ataxia; Neuraminidase 1; Case report; Mucolipidoses

Core Tip: Type 1 sialidosis is a rare autosomal recessive lysosomal storage disorder. Very few cases of this condition have been reported in mainland China, which may be partly attributed to an inadequate awareness of lysosomal storage diseases among neurology physicians. This study reports the clinical and molecular characteristics of a Chinese patient with type 1 sialidosis confirmed by genetic testing. Neuraminidase 1 mutations p.S182G and p.P80L are common pathogenic variants of all three patients identified in Mainland China, coming from three unrelated families.