Test Catalog

Test Id : I2SW

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Iduronate-2-Sulfatase, Blood

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Overview

Test Catalog

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

Diagnosis of mucopolysaccharidosis II (MPS II, Hunter syndrome) in whole blood specimens

 

This test is not useful for determining carrier status for MPS II.

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

This test provides diagnostic testing for individuals with positive newborn screen results or clinical signs and symptoms suspicious for mucopolysaccharidosis type II (MPS II, Hunter syndrome).

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 Enzyme Assay

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

Iduronate-2-sulfatase, B

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

Iduronate-2-sulfatase deficiency

Alpha-L-Idopyranosyluronic Acid 2-Sulfate Sulfahydrolase

Hunter Syndrome

Iduronate 2-Sulfatase Deficiency

MPS 2

MPS II

Mucopolysaccharidosis II

Sulfoiduronate Sulfatase Deficiency

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

Necessary Information

Provide a reason for testing with each specimen.

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

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD)

Specimen Volume: 2 mL

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

0.5 mL

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

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

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 Ambient (preferred) 7 days
Refrigerated 7 days

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

Diagnosis of mucopolysaccharidosis II (MPS II, Hunter syndrome) in whole blood specimens

 

This test is not useful for determining carrier status for MPS II.

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

This test provides diagnostic testing for individuals with positive newborn screen results or clinical signs and symptoms suspicious for mucopolysaccharidosis type II (MPS II, Hunter syndrome).

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, also known as glycosaminoglycans (GAG). Accumulation of GAG in the lysosomes interferes with normal functioning of cells, tissues, and organs. Mucopolysaccharidosis II (MPS II, Hunter syndrome) is an X-linked lysosomal storage disorder caused by the deficiency of iduronate sulfatase (IDS) enzyme and gives rise to the physical manifestations of the disease.

 

Clinical features and severity of symptoms are widely variable ranging from severe infantile onset disease to an attenuated form, which generally has a later onset with a milder clinical presentation. Symptoms may include coarse facies, short stature, enlarged liver and spleen, hoarse voice, stiff joints, cardiac disease, and profound neurologic involvement leading to developmental delays and regression. As an X-linked disorder, MPS II occurs primarily in male patients with an estimated incidence of 1 in 120,000 male births, although symptomatic carrier females have been reported. Treatment availability, including hematopoietic stem cell transplantation and enzyme replacement therapy, makes early diagnosis desirable, as early initiation of treatment has been shown to improve clinical outcomes. Newborn screening for MPS II has been implemented in some states.

 

A diagnostic workup in an individual with MPS II typically demonstrates elevated levels of urinary GAG and increased amounts of both dermatan sulfate and heparan sulfate (see MPSQU / Mucopolysaccharides Quantitative, Random, Urine and MPSBS / Mucopolysaccharides, Blood Spot). Reduced or absent activity of IDS can confirm a diagnosis of MPS II but may also be deficient in unaffected individuals with pseudodeficiency as well as individuals with multiple sulfatase deficiency. Enzymatic testing is not reliable to detect carriers. Molecular genetic testing of the IDS gene allows for detection of the disease-causing variant in affected individuals and subsequent carrier detection in female relatives (see MPS2Z / Hunter Syndrome, Full Gene Analysis, Varies). Currently, no clear genotype-phenotype correlations have been established.(1)

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 =1.5 nmol/hour/mL

Interpretation
Provides information to assist in interpretation of the test results

Results below 1.5 nmol/hour/mL in properly submitted specimens are consistent with iduronate-2-sulfatase deficiency (mucopolysaccharidosis II: MPS II, Hunter syndrome). If clinically indicated, consider further confirmation by molecular genetic analysis of the IDS gene. Note that this enzyme's activity can also be reduced in multiple sulfatase deficiency (MSD).(2) If clinically indicated, consider biochemical genetic testing of other sulfatases or molecular genetic testing of the SUMF1 gene to exclude MSD.

 

Normal results (> or =1.5 nmol/hour/mL) are not consistent with iduronate-2-sulfatase deficiency.

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

The presence of a pseudodeficiency allele may cause reduced activity of iduronate-2-sulfatase in the artificial substrate used in this assay.

 

Enzyme levels may be normal in individuals receiving enzyme replacement therapy or who have undergone bone marrow transplant.

 

Iduronate-2-sulfatase can also be deficient in individuals with multiple sulfatase deficiency.

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

1. D'Avanzo F, Rigon L, Zanetti A, Tomanin R: Mucopolysaccharidosis type II: One hundred years of research, diagnosis, and treatment. Int J Mol Sci. 2020 Feb 13;21(4):1258. doi: 10.3390/ijms21041258

2. Hopwood JJ, Ballabio A: Multiple sulfatase deficiency and the nature of the sulfatase family. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed January 13, 2022. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225546905

3. Neufeld EF, Muenzer J: The Mucopolysaccharidoses. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed January 13, 2022. Available at https://ommbid.mhmedical.com/content.aspx?bookId=2709&sectionId=225544161

4. Scarpa M: Mucopolysaccharidosis type II. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2007. Updated October 4, 2018. Accessed January 13, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1274/

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

The whole blood specimen is spotted onto filter paper and dried overnight. A 3-mm (one-eighth inch) disk is punched out of the dried blood spot into a microcentrifuge tube and inactivated bovine serum albumin is added. The extraction liquid is combined a substrate in a black 96-well plate. A blank is prepared using only preincubation extraction liquid, substrate, and filter paper punch containing no blood. All patients, controls, and blanks are set up in duplicate. After 2 incubations, a stop buffer is added to all wells. Calibrators are prepared and analyzed on every plate to calculate enzyme activity results based on fluorescence units in patient wells versus calibrators. The calibration is derived from 4-methylumbelliferone that is serially diluted manually in the plate, with the highest calibrator being equivalent to an enzyme activity of 3.125 nmol/hour/mL. The plate is then ready to be read using the spectrofluorometer. Fluorescence readings for duplicate wells are averaged, and the average fluorescence is used to calculate the enzyme activity result.(Unpublished Mayo method)

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.

Varies

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.

8 to 15 days

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

1 year

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
I2SW Iduronate-2-sulfatase, B 79462-8
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.
35211 Reviewed By 18771-6
35212 Interpretation (I2SW) 59462-2
61902 Iduronate-2-sulfatase, B 79462-8

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 | Create a 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