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Test ID: MANN Alpha-Mannosidase, Leukocytes

Reporting Name

Alpha-Mannosidase, Leukocytes

Useful For

Diagnosis of alpha-mannosidosis


This test is not useful for establishing carrier status for alpha-mannosidosis.

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 intellectual disability. 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 such as 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 screening assay for several oligosaccharides in urine, OLIGU / Oligosaccharide Screen, Random, Urine. If the urine oligosaccharide screening assay is suggestive of alpha-mannosidosis, enzyme analysis of acid alpha-mannosidase can confirm the diagnosis. Molecular analysis of the MAN2B1 gene allows for detection of a disease-causing variant in affected individuals and subsequent carrier detection in relatives (see CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing; specify MAN2B1 gene list ID: IEMCP-MUMNLV).


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

Report Available

30 to 45 days

Day(s) Performed

Preanalytical processing: Monday through Saturday

Assay performed: Once per month

Clinical Reference

1. Malm D, Nilssen O: Alpha-mannosidosis. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle. 2001. Updated July 18, 2019. Accessed February 18, 2022. Available at

2. Thomas GH: Disorders of glycoprotein degradation: alpha-mannosidosis, beta-mannosidosis, fucosidosis, and sialidosis. 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 February 18, 2022. Available at

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

4. Guffon N, Tylki-Szymanska AT, Borgwardt L, et al: Recognition of alpha-mannosidosis in paediatric and adult patients: Presentation of a diagnostic algorithm from an international working group. Mol Genet Metab. 2019 Apr;126(4):470.474. doi: 10.1016/j.ymgme.2019.01.024

Method Name


Specimen Type

Whole Blood ACD

Ordering Guidance

If clinically suspicious of an oligosaccharidosis, a screening test is available. Order OLIGU / Oligosaccharide Screen, Random, Urine.

Shipping Instructions

For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerate 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.

Specimen Required


Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A)

Specimen Volume: 6 mL

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

Specimen Minimum Volume

5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD Refrigerated (preferred) 6 days YELLOW TOP/ACD
  Ambient  6 days YELLOW TOP/ACD

Reference Values

≥0.54 nmol/min/mg protein

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
MANN Alpha-Mannosidase, Leukocytes 24053-1


Result ID Test Result Name Result LOINC Value
35639 Alpha-Mannosidase, Leukocytes 24053-1
35640 Interpretation (MANN) 59462-2
35641 Reviewed By 18771-6


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.

Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-Pediatric, mml-Neurometabolic