Sanfilippo Syndrome D (MPS IIID): N-Acetylglucosamine-6-Sulfatase Enzyme Analysis

Test Information

This biochemical test is a quantitative measurement of N-acetyl glucosamine-6-sulfatase enzyme activity and can be used as a 1st tier test for patients with a clinical suspicion of Mucopolysaccharidosis IIID (MPS IIID), Sanfilippo syndrome D. Demonstration of deficient N-acetyl glucosamine-6-sulfataseenzyme activity is considered the gold standard to confirm a diagnosis of Mucopolysaccharidosis IIID (MPS IIID), Sanfilippo syndrome D.

In addition, this assay can be used to clarify molecular findings in the GNS gene and to monitor patients undergoing treatment.

Turnaround Time

2 weeks

CPT Code(s)

82657

Cost

$200


Enzymes

N-acetyl glucosamine-6-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 fibroblasts. For leukocytes, please send 5-7 ml of whole blood in a green top (sodium heparin) tube. For fibroblasts, fresh tissue or cultured tissue can be accepted. For cultured tissue, please send two T25 flasks. If cultured tissue is being sent, a control flask is requested in addition to the patient sample. Fresh tissue should be placed in transport media (preferred) or sterile saline. See the link below for additional sample collection and handling instructions.

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. Fibroblasts should be shipped overnight.

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
Falecia Thomas, MS, CGC

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