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Test ID: FUCW Alpha-Fucosidase, Leukocytes

Reporting Name

Alpha-Fucosidase, Leukocytes

Useful For

Detection of fucosidosis


This test is not useful for establishing carrier status for fucosidosis.

Clinical Information

Fucosidosis is an autosomal recessive lysosomal storage disorder caused by reduced or absent alpha-L-fucosidase enzyme activity. This enzyme is involved in degrading asparagine-linked, fucose-containing complex molecules (oligosaccharides and glycoasparagines) present in cells. Reduced or absent activity of this enzyme results in the abnormal accumulation of these molecules in the tissues and body fluids.

Severe and mild subgroups of fucosidosis, designated types I and II, have been described, although recent data suggests individual patients may represent a continuum within a wide spectrum of severity. The more severe type is characterized by infantile onset, rapid psychomotor regression, and severe neurologic deterioration. Additionally, dysostosis multiplex and elevated sweat sodium chloride are frequent findings. Death typically occurs within the first decade of life. Those with the milder phenotype express comparatively mild psychomotor and neurologic regression, radiologic signs of dysostosis multiplex, and skin lesions (angiokeratoma corporis diffusum). Normal sweat salinity, the presence of the skin lesions, and survival into adulthood most readily distinguish milder from more severe phenotypes. Fucosidosis is an autosomal recessive condition resulting from two biallelic pathogenic variants in the FUCA1 gene. Although the disorder is panethnic, the majority of reported patients with fucosidosis have been from Italy and southwestern United States. To date, about 100 cases have been reported worldwide.


An initial diagnostic workup includes a urine screening assay for several oligosaccharidosis (OLIGU / Oligosaccharide Screen, Random, Urine). If the screening assay is suggestive of fucosidosis, enzyme analysis of alpha-L-fucosidase can confirm the diagnosis.


Values below 0.32 nmol/min/mg protein are consistent with a diagnosis of fucosidosis.

Report Available

30 to 45 days

Day(s) Performed

Preanalytical processing: Monday through Saturday

Assay performed: Once per month

Clinical Reference

1. Enns GM, Steiner RD, Cowan TM: Lysosomal disorders. In: Sarafoglou K, Hoffmann GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. McGraw-Hill Medical Division; 2009:747-748

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 17, 2022. Available at:

3. Stepien KM, Ciara E, Jezela-Stanek A. Fucosidosis-clinical manifestation, long-term outcomes, and genetic profile-review and case series. Genes (Basel). 2020 Nov 22;11(11):1383. doi: 10.3390/genes11111383

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

≥0.32 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
FUCW Alpha-Fucosidase, Leukocytes 24047-3


Result ID Test Result Name Result LOINC Value
8814 Alpha-Fucosidase, Leukocytes 24047-3
35635 Interpretation (FUCW) 59462-2
35634 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