While sialidosis is a spectrum and the phenotype varies in clinical onset and severity, two distinct types have been described. Sialidosis type 1 is on the milder end of the spectrum. Onset typically occurs in the second decade and is characterized by progressive loss of vision associated with nystagmus, ataxia, macular cherry-red spots and seizures; but not dysmorphic features. Sialidosis type 2 is on the severe end of the spectrum. It is characterized by dysmorphic features, intellectual disability, developmental delays, macular cherry-red spots, hepatosplenomegaly, dysostosis multiplex, and coarse facies. The age of onset distinguishes the subtypes: congenital or hydropic, infantile (0-12 months), or juvenile (2-20 years). Hydrops fetalis can manifest in the congenital/hydropic subtype.
Mutations in the NEU1 gene (6p21.33) cause sialidosis. Sequence analysis of the entire NEU1 gene coding region is available for individuals suspected of having sialidosis and their at-risk relatives on a clinical basis.
This test is indicated for:
- Confirmation of a clinical diagnosis of sialidosis.
- Carrier testing in adults with a family history of sialidosis.
Analytical Sensitivity: ~99%
Submit only 1 of the following specimen types
Preferred specimen type: Whole Blood
Type: Whole Blood
Specimen Requirements:In EDTA (purple top) or ACD (yellow top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml
Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample within 5 days of collection at room temperature with overnight delivery.
Specimen Requirements:OrageneTM Saliva Collection kit (available through EGL) used according to manufacturer instructions.
Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.
- Oligosaccharide and Glycan Screening (Test Code: OS) is also available.
- Custom diagnostic mutation analysis (Test Code: KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
- Prenatal testing is available for known familial mutations only. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.