They are a spectrum of disorders but two distinct phenotypes have been described. Salla disease, also known as Finnish type sialuria, is on the milder end of the spectrum. It is characterized by neurologic findings at birth that are slowly progressive, leading to mild to moderate psychomotor delays, athetosis, seizures, and spasticity in adulthood. Truncal ataxia and hypotonia typically manifest at about one year of age. Affected individuals appear normal at birth but coarse facial features may develop in adulthood. Infantile free sialic acid storage disease (ISSD) is on the more severe end of the spectrum. It is characterized by severe developmental delay, hepatosplenomegaly, cardiomegaly, and coarse facial features. Death usually occurs in early childhood. Variable expressivity has been observed within families.
Mutations in the SLC17A5 gene (6q13) cause free sialic acid storage disorders. A founder mutation for Salla disease has been described in the Finnish population. Sequence analysis of the entire SLC17A5 gene coding region is available for individuals suspected of having a disorder of free sialic acid metabolism and their at-risk relatives on a clinical basis.
This test is indicated for:
- Confirmation of a clinical diagnosis of free sialic acid storage disorders.
- Carrier testing in adults with a family history of free sialic acid storage disorders.
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) 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.
- Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
- Prenatal testing is available only for known familial mutations to individuals who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.