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Test ID MANN Alpha-Mannosidase, Leukocytes

Reporting Name

Alpha-Mannosidase, Leukocytes

Useful For

Diagnosis of alpha-mannosidosis

Specimen Type

Whole Blood ACD


Shipping Instructions


For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerate within 144 hours of draw to be stabilized. Draw specimen Monday through Thursday only and not the day before a holiday. Specimen should be drawn and packaged as close to shipping time as possible.



Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A)

Specimen Volume: 6 mL

Collection Instructions: Do not transfer blood to other containers.


Specimen Minimum Volume

5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood ACD Refrigerated (preferred) 6 days
  Ambient  4 days

Reference Values

≥0.54 nmol/min/mg protein

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

82657

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MANN Alpha-Mannosidase, Leukocytes In Process

 

Result ID Test Result Name Result LOINC Value
35639 Alpha-Mannosidase, Leukocytes 24053-1
35640 Interpretation (MANN) 59462-2
35641 Reviewed By No LOINC Needed

Clinical Information

Alpha-mannosidosis is an autosomal recessive lysosomal storage disorder caused by reduced or absent acid alpha-mannosidase enzyme activity. This enzyme is involved in glycoprotein catabolism, with absent or reduced activity resulting in the accumulation of undigested mannose-containing complex oligosaccharides in the lysosomes, disrupting the normal functioning of cells.

 

Clinical features and severity of symptoms are widely variable within alpha-mannosidosis but, in general, the disorder is characterized by skeletal abnormalities, immune deficiency, hearing impairment, and mental retardation. Three clinical subtypes of the disorder have been described and vary with respect to age of onset and clinical presentation. Type 1 is generally classified by a mild presentation and slow progression with onset after 10 years of age and absence of skeletal abnormalities. Type 2 is generally a more moderate form with slow progression and onset prior to 10 years of age with skeletal abnormalities and myopathy. Type 3 is the most severe form with onset in early infancy, skeletal abnormalities (dysostosis multiplex), and severe central nervous system involvement. Although treatment is mostly supportive and aimed at preventing complications, hematopoietic stem cell transplant has been reported to be a feasible therapeutic option. The incidence of alpha-mannosidosis is estimated at 1 in 500,000 live births.

 

An initial diagnostic workup may include a multi-enzyme screening assay for several oligosaccharidoses, including mannosidosis in leukocytes or fibroblasts (OLIGU / Oligosaccharide Screen, Urine; OLIWB / Oligosaccharidoses Screen, Leukocytes; or OLITC / Oligosaccharidoses Screen, Fibroblasts). If the screening assay is suggestive of alpha-mannosidosis, enzyme analysis of acid alpha-mannosidase can confirm the diagnosis.

Interpretation

Values below 0.54 nmol/min/mg protein are consistent with a diagnosis of alpha-mannosidosis.

Clinical Reference

1. Malm D, Nilssen O: Alpha-Mannosidosis. In GeneReviews. Edited by RA Pagon, MP Adam, HH Ardinger, et al. University of Washington, Seattle. 2001 Oct 11 (Updated 2012 May 3). Accessed 3/6/2017. Available at www.ncbi.nlm.nih.gov/books/NBK1396/

2. Thomas GH: Chapter 140: Disorders of Glycoprotein Degradation: alpha-mannosidosis, beta-mannosidosis, fucosidosis, and sialidosis. In Scriver's The Online Metabolic and Molecular Basis of Inherited Disease (OMMBID). Edited by D Valle, B Vogelstein, SE Antonarakis, et al. McGraw-Hill Medical Division. Accessed 3/16/2017. Available at http://ommbid.mhmedical.com/

3. Mynarek M, Tolar J, Albert MH, et al: Allogeneic hematopoietic SCT for alpha-mannosidosis: an analysis of 17 patients. Bone Marrow Transplant 2012 Mar;47(3):352-359. doi: 10.1038/bmt.2011.99

Analytic Time

30 days

Method Name

Fluorometric

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