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Test ID: ANAS Alpha-N-Acetylglucosaminidase, Serum

Reporting Name

Alpha-N-Acetylglucosaminidase, S

Useful For

Preferred assay for diagnosis of Sanfilippo syndrome type B (mucopolysaccharidoses type IIIB)

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL


Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen 365 days

Reference Values

0.09-0.58 U/L

Day(s) and Time(s) Performed

Varies

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

84311

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ANAS Alpha-N-Acetylglucosaminidase, S 1837-4

 

Result ID Test Result Name Result LOINC Value
50564 Specimen 31208-2
50565 Specimen ID 57723-9
50566 Source 31208-2
50567 Order Date 82785-7
50568 Reason For Referral 42349-1
50569 Method 49549-9
50577 Alpha-N-Acetylglucosaminidase, S 1837-4
50570 Interpretation 59462-2
50571 Amendment 48767-8
50572 Reviewed By No LOINC Needed
50573 Release Date 82772-5

Clinical Information

The mucopolysaccharidoses (MPS) are a group of disorders caused by the deficiency of any of the enzymes involved in the stepwise degradation of dermatan sulfate, heparan sulfate, keratan sulfate, or chondroitin sulfate (glycosaminoglycans GAG). Accumulation of GAG in lysosomes interferes with normal functioning of cells, tissues, and organs resulting in the clinical features observed in MPS disorders.

 

Sanfilippo syndrome (MPS type III) is an autosomal recessive MPS with 4 recognized types (A-D). Each type is caused by a deficiency in 1 of 4 enzymes involved in the degradation of heparan sulfate resulting in its lysosomal accumulation. Though biochemically different, the clinical presentation of all types is indistinguishable. Sanfilippo syndrome is characterized by severe central nervous system (CNS) degeneration, but other symptoms seen in MPS, such as coarse facial features and skeletal involvement, tend to be milder. Onset of clinical features usually occurs between 2 and 6 years in a child who previously appeared normal. The presenting symptoms are most commonly developmental delay and severe behavioral problems. 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 individuals with an attenuated phenotype may have a longer life expectancy and remain functional into their third and fourth decades.

 

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. Affected individuals demonstrate elevations of heparan sulfate in urine. Diagnostic sequencing of the NAGLU gene (MP3BZ / Mucopolysaccharidosis IIIB, Full Gene Analysis) and deletion/duplication studies are available for patients with an enzyme deficiency.

 

Patients with Mucolipidosis II/III (I-cell disease) may demonstrate elevations of alpha-N-acetylglucosaminidase in addition to abnormalities of other hydrolases. I-cell disease is an autosomal recessive lysosomal storage disorder resulting in impaired transport and phosphorylation of newly synthesized lysosomal proteins to the lysosome due to deficiency of N-acetylglucosamine 1-phosphotransferase (GlcNAc). Characteristic clinical features include short stature, skeletal and cardiac abnormalities, and developmental delay. Measurement of alpha-N-acetylglucosaminidase activity is not the preferred diagnostic test for I-cell disease but may be included in the testing strategy.

Interpretation

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

Clinical Reference

1. Heron B, Mikaeloff Y, Froissart R, et al: Incidence and natural history of mucopolysaccharidosis type III in France and comparison with United Kingdom and Greece. Am J Med Genet A 2011;155A(1):58-68

2. Neufeld EF, Muenzer J: Chapter 136: The Mucopolysaccharidoses. In The Metabolic and Molecular Bases of Inherited Disease. Eighth edition. Edited by D Valle, AL Beaudet, B Vogelstein, et al. New York, McGraw-Hill Book Company. Accessed 01/13/2015. Available at www.ommbid.com

3. Valstar MJ, Bruggenwirth HT, Olmer R, et al: Mucopolysaccharidosis type IIIB may predominantly present with an attenuated clinical phenotype. J Inherit Metab Dis 2010;33:759-767

4. Neufeld EF, Muenzer J: Neufeld E.F., Muenzer J Neufeld, Elizabeth F., and Joseph Muenzer.The Mucopolysaccharidoses. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, AL Beaudet, B Vogelstein, et al. Valle D, Beaudet A.L., Vogelstein B, Kinzler K.W., Antonarakis S.E., Ballabio A, Gibson K, Mitchell G Eds. David Valle, et al.New York, NY: McGraw-Hill; 2014. Accessed March 09, 2017. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62642135

Analytic Time

30 days

Method Name

Colorimetric

Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. Biochemical Genetics Patient Information (T602) in Special Instructions

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical