Preferred enzymatic test for detection of arylsulfatase A deficiency
This test is not suitable for carrier detection.
For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.
Send specimen in original tube. Do not aliquot.
This test is not reliable in identifying carriers due both to analytical variation and unusual genetic variants.
Arylsulfatase A is also deficient in individuals with multiple sulfatase deficiency.
This disorder is distinct from conditions caused by deficiencies of arylsulfatase B (Maroteaux-Lamy disease) and arylsulfatase C (steroid sulfatase deficiency).
This is the preferred test to rule-out metachromatic leukodystrophy.
Metachromatic leukodystrophy (MLD) is caused by deficient activity of arylsulfatase A (ARSA) enzyme and is characterized by progressive neurologic changes and leukodystrophy with variable age of onset.
Pseudodeficiency of arylsulfatase A (ARSA) enzyme has been recognized with increasing frequency among patients with other apparently unrelated neurologic conditions as well as among the general population.
Additional studies, such as molecular genetic testing of ARSA (ARSAZ / ARSA Gene, Full Gene Analysis, Varies), urinary excretion of sulfatides (CTSU / Ceramide Trihexosides and Sulfatides, Random, Urine), and/or histological analysis for metachromatic lipid deposits in nervous system tissue are recommended to confirm a diagnosis.
> or =62 nmol/h/mg
Note: Results from this assay may not reflect carrier status because of individual variation of arylsulfatase A enzyme levels. Low normal values may be due to the presence of pseudodeficiency gene variant or carrier gene variant. Patients with these depressed levels may be phenotypically normal.
Reduced levels of arylsulfatase A are seen in patients with metachromatic leukodystrophy (MLD).
Individuals with pseudodeficiency of arylsulfatase A can have results in the affected range but are otherwise unaffected with MLD.
Abnormal results should be confirmed using CTSU / Ceramide Trihexosides and Sulfatides, Random, Urine. If molecular confirmation is desired, consider molecular genetic testing ARSAZ / ARSA Gene, Full Gene Analysis, Varies.