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sialidosis; mucolipidosis 1; lipomucopolysaccharidosis; sialidase deficiency; glycoprotein neuraminidase deficiency; neuraminidase 1 deficiency; cherry red spot-myoclonus syndrome
Classification:
- sialidosis type 1 (milder form, normosomatic type)
- sialidosis type 2 (dysmorphic type)
Epidemiology: rare
Pathology:
1) deficiency of the enzyme neuraminidase
2) progressive lysosomal storage of sialidated glycopeptides & oligosaccharides
3) accumulation &/or excretion of sialic acid covalently linked to a variety of oligosaccharides &/or glycoproteins
4) cytoplasmic vacuolation of peripheral lymphocytes, bone marrow cells & conjunctival epithelial cells
Genetics:
- defects in NEU1 are the cause of sialidosis
- chromosomal rearrangement involving CTL4 & NEU1
Clinical manifestations:
1) presentation (infancy to 3rd decade of life)
2) type 1:
a) late-onset
b) formation of macular cherry red spots in childhood
c) progressive debilitating myoclonus
d) insiduous visual loss
e) ataxia (rare)
3) type 2:
a) occurs as several variants of increasing severity with earlier age of onset
b) abnormal somatic features
- coarse facies
- dysostosis multiplex
- short trunk
- barrel chest
- vertebral deformities
- macular cherry red spots
- inner ear hearing loss
c) neurologic abnormalities
- muscular hypotonia & hypotrophy, ataxia, myoclonus, & seizures, cerebellar syndrome, intellect low-normal, progressive neurodegeneration
d) early demise, depending upon severity
Laboratory:
- sialic acid in urine
- urine sialyloligosaccharide (present)
- sialuria
Related
solute carrier family 44 member 4 (SLC44A4, choline transporter-like protein 4, C6orf29, CTL4, NG22, UNQ441/PRO874)
General
mucopolysaccharidosis (MPS)
Database Correlations
OMIM 256550
References
OMIM :accession 256550