Mucopolysaccharidosis IIIA (MPS IIIA), Sanfilippo syndrome A : Heparan-N-sulfatase Enzyme Analysis

Test Information

This biochemical test is a quantitative measurement of Heparan-N-sulfatase enzyme activity and can be used as a 1st tier test for patients with a clinical suspicion of Mucopolysaccharidosis IIIA (MPS IIIA)/Sanfilippo A syndrome. Demonstration of deficient Heparan-N-sulfatase enzyme activity is considered the gold standard to confirm a diagnosis of Mucopolysaccharidosis IIIA (MPS IIIA)/Sanfilippo A syndrome.

In addition, it can be used to clarify molecular findings in the SGSH gene and to monitor patients undergoing treatment.

Turnaround Time

2 weeks

CPT Code(s)

82657

Cost

$200


Enzymes

Heparan-N-sulfatase

Clinical Information

Sanfilippo syndrome is characterized by progressive developmental delay and behavioral problems. These patients have fewer of the somatic concerns seen in other types of MPS disorders.

Sanfilippo syndrome is caused by a defect in one of four enzymes required for the modification and removal of glucosamine residues from heparan sulfate. A defect in one of these four enzymes (types A-D) results in the accumulation of heparan sulfate in the patient�s cells and organs which overtime leads to the clinical phenotype. Patients with Sanfilippo syndrome experience delayed development with a progressively deteriorating mental status. Behavior and sleep problems are common as well as coarse facial features and stiff joints. The four types of Sanfilippo syndrome (A-D) are clinically indistinguishable, thus enzyme testing is recommended as an initial diagnostic test.

Indications

There are four enzymatically distinct forms of Sanfilippo syndrome with significant clinical overlap. Enzymatic testing is necessary to further distinguish between the following four types. These four enzymes are required for the modification and removal of glucosamine residues from heparan sulfate. These defects result in the accumulation of heparan sulfate in the patient�s cells and organs which overtime leads to the clinical phenotype. Enzyme analysis for each type of Sanfilippo syndrome may be ordered individually or as a panel.

Methodology

4-methylumbelliferyl substrate

Specimen Requirements

Enzyme activity can be measured in leukocytes or cultured fibroblasts. For leukocytes, please send 5-7 ml of whole blood in a green top (sodium heparin) tube.

Transport Instructions

Whole blood should be sent over overnight at ambient temperature. Do not freeze whole blood. Samples for enzyme analysis must arrive to the lab within 24 hours of blood draw.

Cultured fibroblasts can be sent overnight at room temperature.

Have Questions Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Kellie Walden, MS, CGC

Biochemical Testing, Enzyme Analysis, Individual Enzyme Assays
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