Test Catalog

Test Id : G6SW

N-Acetylgalactosamine-6-Sulfatase, Leukocytes

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

Preferred test to rule-out mucopolysaccharidosis IVA (Morquio A syndrome)

 

The test is not useful for establishing carrier status for Morquio A syndrome.

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

This is the preferred test to rule-out mucopolysaccharidosis IVA, (MPS IVA; Morquio A syndrome).

 

Morquio A is an autosomal recessive mucopolysaccharidosis caused by reduced or absent N-acetylgalactosamine-6-sulfate sulfatase enzyme activity.

 

Although clinically similar, Morquio A is distinct from Morquio B at the molecular and enzyme levels. Enzyme analysis is necessary to distinguish between the two.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Fluorometric

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

N-Acetylgalactosamine 6 Slft, WBC

Aliases
Lists additional common names for a test, as an aid in searching

Galactosamine-6-Sulfatase Deficiency

Galactosamine-6-Sulfatase

Galactose-6-Sulfatase

Morquio Syndrome

Morquio Syndrome A

Morquio Syndrome Type A

MPS 4A

MPS IVA

Mucopolysaccharidosis

Galactose-6-Sulphatase

Morquio A Disease

Morquio A

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type
Describes the specimen type validated for testing

Whole Blood ACD

Ordering Guidance

This test cannot be used to establish carrier status for Morquio A syndrome; sequencing of the GALNS gene is recommended. Order CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies and specify Gene List ID: EMCP-JUFPRX.

Shipping Instructions

For optimal isolation of leukocytes, it is recommended the specimen arrive within 7 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A)

Specimen Volume: 6 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

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.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Whole Blood ACD Refrigerated (preferred) 7 days YELLOW TOP/ACD
Ambient 7 days YELLOW TOP/ACD

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

Preferred test to rule-out mucopolysaccharidosis IVA (Morquio A syndrome)

 

The test is not useful for establishing carrier status for Morquio A syndrome.

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

This is the preferred test to rule-out mucopolysaccharidosis IVA, (MPS IVA; Morquio A syndrome).

 

Morquio A is an autosomal recessive mucopolysaccharidosis caused by reduced or absent N-acetylgalactosamine-6-sulfate sulfatase enzyme activity.

 

Although clinically similar, Morquio A is distinct from Morquio B at the molecular and enzyme levels. Enzyme analysis is necessary to distinguish between the two.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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

The mucopolysaccharidoses 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 (referred to as mucopolysaccharides [MPS] or glycosaminoglycans). Accumulation of MPS in lysosomes interferes with normal functioning of cells, tissues, and organs.

 

Mucopolysaccharidosis IVA, (MPS IVA; Morquio A syndrome) is an autosomal recessive mucopolysaccharidosis caused by reduced or absent N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme activity. The glycosaminoglycans, keratan and chondroitin sulfate, accumulate in multiple tissues but mainly bone, cartilage, heart valves, and cornea.  Clinical features and severity of symptoms of MPS IVA are widely variable affecting multiple body systems, in particular the skeletal system. Other clinical features may include short stature, dental anomalies, corneal clouding, respiratory insufficiency, and cardiac disease. Intelligence is usually normal. Treatment options are mostly limited to symptom management; however, more recently available enzyme replacement therapy has shown to be effective in improving some function and quality of life for individuals with MPS IVA. Estimates of the incidence of MPS IVA syndrome range from 1 in 200,000 to 1 in 300,000 live births.

 

A diagnostic workup in an individual with MPS IVA typically demonstrates elevated urinary levels of keratan sulfate and chondroitin-6-sulfate. Reduced or absent activity of N-acetylgalactosamine-6-sulfate sulfatase enzyme in leukocytes and/or fibroblasts can confirm the diagnosis. Sequencing of the GALNS gene (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify Gene List ID: EMCP-JUFPRX) allows for detection of disease-causing variants in affected patients and identification of familial variants allows for testing of at-risk family members. Morquio B is a distinct disorder caused by a deficiency of beta-galactosidase and has a significant number of overlapping clinical features with MPS IVA. Enzyme analysis (BGAW / Beta-Galactosidase, Blood) is necessary to distinguish between the 2 types.

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.

> or =92 nmol/17 hour/mg protein

Interpretation
Provides information to assist in interpretation of the test results

Very low enzyme activity levels are consistent with mucopolysaccharidosis IVA (Morquio A syndrome).

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

No significant cautionary statements

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Hendriksz CJ, Harmatz P, Beck M, et al: Review of clinical presentation and diagnosis of mucopolysaccharidosis IVA. Mol Genet Metab. 2013 Sep-Oct;110(1-2):54-64. doi: 10.1016/j.ymgme.2013.04.002

2. Sawamoto K, Alvarez Gonzalez JV, Piechnik M, et al. Mucopolysaccharidosis IVA: Diagnosis, treatment, and management. Int J Mol Sci. 2020 Feb 23;21(4):1517. doi: 10.3390/ijms21041517

3. Haddley K: Elosulfase alfa. Drugs Today (Barc). 2014 Jul;50(7):475-483. doi: 10.1358/dot.2014.50.7.2177904

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) results from a deficiency of the N-acetylgalactosamine-6-sulfate sulfatase enzyme. This enzyme hydrolyzes a sulfate group from the 6 position of galactose at the nonreducing terminus of the mucopolysaccharides, keratin sulfate and chondroitin-6 sulfate. In this procedure, 4- methylumbelliferyl (MU)-beta-D-galactoside-6-sulfate is used as the substrate. The enzyme will cleave the 6-sulfate from the galactose residue and a second incubation with excess beta-galactosidase will cleave the 4MU, which is measured fluorometrically and calculated against a calibration of 4MU.(Package insert: Laboratory protocol for enzyme analysis for Morquio A disease [MPS IV A]. Moscerdam Substrates; van Diggelen OP, Zhao H, Kleijer WJ, et al: A fluorimetric enzyme assay for the diagnosis of Morquio disease type A. Clin Chim Acta. 1990;187:131-140; Cowan T, Pasquali M: Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. 2017:1139-1158)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Preanalytical processing: Monday through Saturday

Assay performed: Once per month

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

30 to 45 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

WBC homogenate: 1 month

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

82657

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
G6SW N-Acetylgalactosamine 6 Slft, WBC 24096-0
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
62409 N-Acetylgalactosamine 6 Slft, WBC 24096-0
35778 Interpretation (G6SW) 59462-2
35777 Reviewed By 18771-6

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports