Test ID: ANAT
Alpha-N-Acetylglucosaminidase, Fibroblasts
Useful For 
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of Sanfilippo syndrome, type B (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 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.
0.076-0.291 U/g of cellular protein
Interpretation Provides information to assist in interpretation of the test results
Deficiency of alpha-N-acetylglucosaminidase is diagnostic for Sanfilippo syndrome 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
The preferred specimen type for diagnosing Sanfilippo syndrome type B is serum (ANAS/8782 Alpha-N-Acetylglucosaminidase, Serum); however, if fibroblasts are readily available, this test can also be used to diagnose this disorder.
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 syndrome type B.
Interfering factors include lack of viable cells, bacterial contamination, failure to transport tissue in an appropriate media, excessive transport time, and exposure of the specimen to temperature extremes (freezing or >30 degrees C).
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
External
link
PDF
document
Excel
document
Word
document