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  • Updated 05.01.2024
  • Released 04.19.1995
  • Expires For CME 05.01.2027




Fucosidosis is an autosomal recessive disorder resulting from a deficiency of alpha-L-fucosidase, encoded by the FUCA1 gene. Individual patients may represent a continuum within a wide spectrum of severity. The more severely affected patients present within the first year of life with psychomotor retardation, coarse facies, growth retardation, and dysostosis multiplex. Patients with milder phenotypes develop angiokeratoma and have longer survival. The enzyme defect results in the accumulation and excretion of a variety of glycoproteins, glycolipids, and oligosaccharides containing fucoside moieties. Diagnosis should be suspected on detection of excess oligosaccharides in urine but must be confirmed by demonstrating low alpha-L-fucosidase activity in peripheral white blood cells. MRI and MR spectroscopy are of substantial diagnostic value. Pallidal lesions resembling the eye-of-the-tiger sign suggest iron accumulation.

Key points

• Fucosidosis presents with a spectrum of neurologic and skeletal abnormalities.

• Fucosidosis is caused by a deficiency of alpha-L-fucosidase, encoded by the FUCA1 gene.

• Typical MRI features of fucosidosis combine globi pallidi hyperintensity on T1-weighted images that are hypointense on T2-weighted images with diffuse hypomyelination.

• Proton MR spectroscopy may show specific diagnostic abnormalities in patients with fucosidosis.

• Early hematopoietic stem cell transplantation should be considered in patients with the less aggressive form of fucosidosis.

Historical note and terminology

Fucosidosis, a progressive mental retardation syndrome involving lysosomal storage, was first described by Italian pediatrician Paolo Durand and colleagues in 1966 (12; 13). Fucosidosis involves both fuco-oligosaccharide and fuco-glycosphingolipid storage (09). One of the original names for the disease, "mucolipidosis F," was derived from the second patient to be described (36) because the phenotype was reminiscent of patients with mucopolysaccharide storage diseases. Other forms of fucosidosis show angiokeratomas reminiscent of Fabry disease without substantial skeletal abnormalities (65; 21). Numerous phenotypes are unrelated to either the genotype or the resulting level of residual enzyme activity. The FUCA1 gene and a pseudogene, FUCA1P, have been cloned, and numerous mutations have been shown to cause fucosidosis (17; 68; 54; 55; 53; 56; 67).

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