Supporting the biochemical diagnosis of mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome) in whole blood specimens
This test is not useful for carrier detection.
This test provides diagnostic testing for individuals with clinical signs and symptoms suspicious for mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome). If an enzyme deficiency is detected by this test, additional biochemical or molecular testing is required to confirm a diagnosis.
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
ARSW
Arylsulfatase B
Maroteaux Lamy syndrome
MPS 6
MPS VI
Mucopolysaccharidosis VI
N-acetyl galactosamine-4-sulfatase
Whole Blood ACD
For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 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.
1. Patient's age is required.
2. Reason for testing is required.
Question ID | Description | Answers |
---|---|---|
BG761 | Reason for Referral |
Rule out MPS VI Follow up of known MPS VI Not Provided |
Container/Tube:
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A) or lavender top (EDTA)
Specimen Volume: 6 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
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.
5 mL
Gross hemolysis | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Whole Blood ACD | Refrigerated (preferred) | 6 days | |
Ambient | 6 days |
Supporting the biochemical diagnosis of mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome) in whole blood specimens
This test is not useful for carrier detection.
This test provides diagnostic testing for individuals with clinical signs and symptoms suspicious for mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome). If an enzyme deficiency is detected by this test, additional biochemical or molecular testing is required to confirm a diagnosis.
Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy syndrome) is an autosomal recessive lysosomal disorder caused by the deficiency of N-acetylgalactosamine 4-sulfatase, also known as arylsulfatase B (ARSB) leading to the accumulation of dermatan sulfate. Clinical features and severity of symptoms are widely variable, but typically include short stature, dysostosis multiplex, and degenerative joint disease. Other clinical features may include facial dysmorphism, hepatosplenomegaly, corneal clouding, and cardiac disease. Intelligence is usually normal. Rapidly progressing forms have an early onset of symptoms, significantly elevated GAGs, and can lead to death before the second or third decades. A more slowly progressing form has a later onset, milder skeletal manifestations, smaller elevations of GAGs, and typically a longer lifespan. Treatment options include hematopoietic stem cell transplantation and/or enzyme replacement therapy.
The differential diagnosis of ARSB deficiency should include multiple sulfatase deficiency and mucolipidosis II (I-Cell disease), however both conditions present with developmental delays that make them clinically different from MPS VI. The symptoms of MSD mimic metachromatic leukodystrophy (MLD) as well as the mucopolysaccharidoses and can include developmental delay, neurologic regression, dysmorphic facies, dysostosis multiplex, organomegaly, ichthyosis, and chondroplasia punctata. If MSD is suspected, testing of an additional sulfatase enzyme, such as arylsulfatase A (ARSAW/ Arylsulfatase A, Leukocytes) in MLD, can help determine if multiple sulfatases are deficient. I-cell disease is characterized by congenital or early infantile manifestations including coarse facial features, short stature, skeletal anomalies, cardio- and hepatomegaly, and developmental delays. This is a progressive disorder and death typically occurs in the first decade of life. Additional testing including hydrolase enzymes in serum, such as hexosaminidase A in Tay-Sach disease (NAGS/ Hexosaminidase A and Total Hexosaminidase, Serum) is recommended if a diagnosis of I-cell is suspected.
A diagnostic workup for MPS includes glycosaminoglycan (GAG) determination in urine (MPSQU / Mucopolysaccharides Quantitative, Random, Urine) or blood (MPSBS / Mucopolysaccharidosis, Blood Spot, or MPSER / Mucopolysaccharidosis, Serum) and molecular genetic analysis of the relevant gene. For MPS VI, molecular analysis of the ARSB gene (CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies; specify Gene List ID: IEMCP-QQF7DP) allows for detection of disease-causing variant in affected patients and subsequent carrier detection in relatives.
>0.34 nmol/hour/mg protein
An interpretive report will be provided.
Abnormal results are not sufficient to establish a diagnosis of a particular disease. To verify a preliminary diagnosis based on this assay, additional biochemical or molecular genetic analyses are required.
When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing, and in vitro, confirmatory studies (enzyme assay, molecular analysis), and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.
Individuals with pseudodeficiency alleles can show reduced enzyme activity.
Carrier status (heterozygosity) for these conditions cannot be reliably detected.
Enzyme levels may be normal in individuals receiving enzyme replacement therapy or who have undergone hematopoietic stem cell transplant.
1. Neufeld EF, Muenzer J. The mucopolysaccharidoses. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA. eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; Accessed July 14, 2023. https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225544161
2. Hopwood JJ, Ballabio A. Multiple sulfatase deficiency and the nature of the sulfatase family. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA. eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; Accessed July 14, 2023. https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225546905
Leukocytes are incubated with four cocktail mixes: 1) substrate and internal standard (IS) for iduronate 2-sulfatase, heparan N-sulfatase, alpha-N-acetylglucosaminidase, N-acetylgalactosamine-sulfate, beta-galactosidase, arylsulfatase B, beta-glucuronidase, and tripeptidyl peptidase 1; 2) substrate and IS for acetyl-CoA:alpha-glucosaminide N-acetyltransferase; 3) substrate and IS for N-acetylglucosamine-6-sulfatase; and 4) substrate and IS for palmitoyl-protein thioesterase 1 in 96-well plates. Following overnight incubation, the plates are combined and purified by liquid-liquid extraction. The extracts are evaporated, reconstituted with mobile phase, and analyzed by tandem mass spectrometry.(Unpublished Mayo method)
Preanalytical processing: Monday through Saturday
Testing performed: Tuesday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
82657
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
ARSBW | Arylsulfatase B, WBC | 24094-5 |
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.
|
---|---|---|
BG761 | Reason for Referral | 42349-1 |
616835 | Arylsulfatase B | 24094-5 |
618450 | Interpretation | 59462-2 |
618449 | Reviewed By | 18771-6 |