Metachromatic Leukodystrophy – Enzyme Analysis
|Disease name||Metachromatic leukodystrophy|
|Enzyme Name||Arylsulfatase A|
|Clinical info||Metachromatic leukodystrophy is an autosomal recessive condition caused by a deficiency of arylsulfatase A, an enzyme crucial to the breakdown of sulfatides in the body. Metachromatic leukodystrophy should be considered in any individual with progressive neurological dysfunction and MRI evidence of a leukodystrophy. This condition can present in late-infantile, juvenile and adult forms.|
|Indications||Patients with a suspected diagnosis of metachromatic leukodystrophy through clinical symptoms and MRI findings. Prenatal diagnosis and carrier testing via enzyme analysis are not available.|
|Methodology||Measurement of enzyme activity|
|Specimen Requirements||Enzyme activity can be measured in leukocytes, cultured fibroblasts, or dried blood spots. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube. For dried blood spot collection, a minimum of three circles need to be filled in. Each circle should contain one drop of blood (about 100 microliters). See the link below for additional sample collection and handling instructions.
Sample Collection and Requirements
In addition, a dried blood spot or blood drawn in an EDTA tube can be used for Arylsulfatase A molecular analysis and may be sent for DNA banking. Please indicate on the requisition if DNA should be banked for follow-up molecular testing.
|Transport||Whole blood samples (for leukocyte analysis) should be shipped at ambient temperature and must arrive at the laboratory within 24 hours of blood draw. Please contact the laboratory before transporting tissue for enzyme assay. Fresh tissue for culture should be sent by courier or 24-hour delivery.
For a dried blood spot: When the sample has dried 3-4 hours, fold cover at score line, over sample, and tuck into flap. Samples should be placed in the mail within 24 hours of collection. Overnight shipping is preferred.
|Turnaround time||14 days
Cell culture can take 1-4 weeks and may lengthen turnaround time.
|Cost||Leukocytes or cultured fibroblasts: $200
Dried Blood Spot Analysis: A 50% discount will be applied for enzyme analysis from a dried blood spot reducing the price to $100.
The Biochemical Lab provides diagnostic and screening tests for a variety of inherited metabolic disorders.