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Test ID: ANAS
Alpha-N-Acetylglucosaminidase, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of type B Sanfilippo disease (MPS, type IIIB)

Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request

Diagnostic enzyme assay for Sanfilippo syndrome, type B.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Deficiency of enzymes catalyzing the degradation of glycosaminoglycans (mucopolysaccharides) results in a group of lysosomal storage disorders called mucopolysaccharidoses (MPS). Lysosomal accumulation of glycosaminoglycan molecules eventually results in cell, tissue, and organ dysfunction. There are 10 known enzyme deficiencies that result in 6 distinct MPS, including Sanfilippo syndrome (MPS III).

 

Patients with Sanfilippo syndrome make up a biochemically diverse, but clinically similar group of 4 recognized types (types A-D). Sanfilippo syndrome is characterized by severe central nervous system (CNS) degeneration, but only mild somatic disease. Such disproportionate involvement of the CNS is unique among the MPS. Onset of clinical features usually occurs between 2 and 6 years in a child who previously appeared normal. Severe neurologic degeneration occurs in most patients by 6 to 10 years of age, accompanied by a rapid deterioration of social and adaptive skills. Death generally occurs by age 20. Although there is no cure for Sanfilippo syndrome, research of therapies has included bone marrow transplantation, enzyme replacement, and gene replacement.

 

Sanfilippo syndrome type B is due to the absence of the enzyme N-acetyl-alpha-D-glucosaminidase (alpha-hexosaminidase), caused by mutations in the NAGLU gene. Diagnostic sequencing of the NAGLU coding region and deletion/duplication studies are clinically available for patients with an enzyme deficiency. Refer to www.genetests.org for a listing of laboratories currently offering this testing.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

0.09-0.58 U/L

Interpretation Provides information to assist in interpretation of the test results

Deficiency of alpha-N-acetylglucosaminidase is diagnostic for Sanfilippo type B.

 

See Lysosomal Storage Disorders in Special Instructions for further information on lysosomal storage diseases.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This assay detects Sanfilippo syndrome type B only. The 3 other types of Sanfilippo syndrome (A, C, and D) must be ruled out independently.

 

This assay will not identify carrier status for Sanfilippo type B.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

Neufeld EF, Muenzer J: The mucopolysaccharidoses. In The Metabolic and Molecular Bases of Inherited Disease. 8th edition. Edited by CR Scriver, AL Beaudet, D Valle, et al. New York, McGraw-Hill Book Company, 2001, pp 3421-3452

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test