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Test Code ARSAB Arylsulfatase A, Blood Spot


Ordering Guidance


This test primarily serves as a second-tier assay to be used by newborn screening programs to screen for metachromatic leukodystrophy when first tier sulfatide analysis is abnormal. The test can also be used to screen patients at risk for metachromatic leukodystrophy.



Specimen Required


Supplies: Card-Blood Spot Collection (Filter Paper) (T493)

Container/Tube:

Preferred: Card-Blood Spot Collection (Filter Paper)

Acceptable: PerkinElmer 226 filter paper, Munktell filter paper, Whatman protein Saver 903 paper, local newborn screening card, or blood collected in tubes containing EDTA (preferred) or heparin and dried on filter paper

Specimen Volume: 2 Blood spots

Collection Instructions:

1. Completely fill at least 2 circles on the filter paper card (approximately 100 microliters blood per circle).

2. Let blood dry on filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry and freeze (with desiccant if necessary).

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)


Genetics Test Information

Metachromatic leukodystrophy 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 ARSA enzyme has been recognized among patients with other unrelated neurologic conditions as well as among the general population.

 

Additional studies, such as molecular genetic testing of ARSA (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify ARSA Gene List ID: IEMCP-WHFH2K), urinary excretion of sulfatides (CTSU / Ceramide Trihexosides and Sulfatides, Random, Urine), and, if necessary, histological analysis for metachromatic lipid deposits in nervous system tissue are recommended to confirm a diagnosis.

Specimen Type

Whole blood

Specimen Minimum Volume

1 Blood spot

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Frozen (preferred) 28 days FILTER PAPER
  Refrigerated  14 days FILTER PAPER

Reject Due To

Blood spot specimen that shows serum rings or has multiple layers Reject
Nonapproved filter paper Reject

Reference Values

Normal: ≥0.100 mmol/mL/hr

Day(s) Performed

Monday, Thursday

Report Available

3 to 6 days

Specimen Retention Time

6 months

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82657