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Test ID: ANAS Alpha-N-Acetylglucosaminidase, Serum

Reporting Name

Alpha-N-Acetylglucosaminidase, S

Useful For

Diagnosis of Sanfilippo syndrome type B (mucopolysaccharidoses type IIIB)


This test is not suitable for carrier detection.

Specimen Type


Specimen Required

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial

Specimen Minimum Volume

0.8 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen 365 days

Reference Values

0.09-0.58 U/L

Day(s) Performed

Once per month

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 US Food and Drug Administration.

CPT Code Information


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 85069-3
50577 Alpha-N-Acetylglucosaminidase, S 1837-4
50570 Interpretation 59462-2
50571 Amendment 48767-8
50572 Reviewed By 18771-6
50573 Release Date 82772-5

Clinical Information

The mucopolysaccharidoses (MPS) are a group of disorders caused by a 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 intra- and extra-cellular accumulation. Though biochemically different, the clinical presentation of all types is indistinguishable. Sanfilippo syndrome is characterized by severe central nervous system degeneration, but other symptoms seen in MPS, such as coarse facial features and skeletal involvement, tend to be milder. It is important to note the variability in severity for MPSIII. In some patients, only moderate intellectual disability can be observed even at the end of the third decade of life. However, 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 a deficiency of the enzyme N-acetyl-alpha-D-glucosaminidase (alpha-hexosaminidase), caused by variants in the NAGLU gene. Affected individuals demonstrate elevations of heparan sulfate in blood and urine (MPSBS / Mucopolysaccharidosis, Blood Spot and MPSQU / Mucopolysaccharides Quantitative, Random, Urine). Diagnostic sequencing and deletion/duplication studies of the NAGLU gene (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify NAGLU Gene List ID: IEMCP-KG2Q99) is available for patients with an enzyme deficiency.


Elevations in serum of alpha-N-acetylglucosaminidase and other hydrolases may be seen in patients with mucolipidosis II/III (I-cell disease).(1) 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.


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

Clinical Reference

1. Braulke T, Raas-Rothschild A, Kornfeld S: I-cell disease and pseudo-Hurler polydystrophy: Disorders of lysosomal enzyme phosphorylation and localization. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds: The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed May 24, 2021. Available at

2. Joanna Jakobkiewicz-Banecka, Magdalena Gabig-Ciminska, Anna Kloska, et al. Glycosaminoglycans and mucopolysaccharidosis type III. Frontiers in Bioscience-Landmark. 2016 Jun. 21; 1393-1409.

3. Neufeld EF, Muenzer J: The mucopolysaccharidoses. In: Valle D, Beaudet AL, Vogelstein B, et al; eds. The Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed May 24, 2021. Available at

4. Valstar MJ, Bruggenwirth HT, Olmer R, et al: Mucopolysaccharidosis type IIIB may predominantly present with an attenuated clinical phenotype. J Inherit Metab Dis. 2010 Dec;33(6):759-767. doi: 10.1007/s10545-010-9199-y

5. Beneto N, Vilageliu L, Grinberg D, Canals I: Sanfilippo syndrome: Molecular basis, disease models and therapeutic approaches. Int J Mol Sci. 2020 Oct;21(21):7819. doi: 10.3390/ijms21217819

Report Available

30 to 45 days

Method Name



1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602)

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

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