Definition:
Fucosidosis is a rare lysosomal disorder affecting fewer than one in two million individuals. It is one of nine identified Glycoprotein Storage Diseases. Fucosidosis is caused by lack of the enzyme, alpha-fucosidase. This enzyme normally cleaves long sugar chains known as oligosaccharides in the lysosome. When the enzyme is absent, sugar chains accumulate and eventually lead to the clinical features of Fucosidosis. The symptoms of this disorder may progress in degrees of severity over time.

There are two different types of Fucosidosis, Type I and Type II, characterized by the age of onset and by the types of physical and mental manifestations of the disorder.

Symptoms:
Fucosidosis Type I typically appears in the first three to 18 months of life. Symptoms include coarsening of facial features, a large liver, spleen and/or heart, and abnormal bone deformities.  Cherry-red spots may be present on the surface of the eye. Mental retardation and seizures are also present.  Additionally, sweat chloride may be elevated.  Fucosidosis Type I results in a rapid deterioration of the neurologic system.
 
Type II Fucosidosis appears between 12 and 24 months of life.  Children affected usually have mild coarsening of facial features, abnormal bone deformities, mental retardation, and an enlarged liver, spleen and/or heart. In addition, angiokeratomas may also appear. Twisted blood vessels within the membrane covering of the eye and inner eyelid are characteristic features of Type II Fucosidosis.

Inheritance Pattern:
Fucosidosis is an autosomal recessive disorder.

Diagnosis and Testing:
The diagnosis of Fucosidosis is made first by screening the urine for increased concentration of oligosaccharides, short chains of sugars that accumulate in the urine and other tissues.  The diagnosis is then confirmed by measuring the activity of the enzyme alpha-fucosidase in blood or tissue biopsies.  Prenatal diagnosis may be performed by measuring enzyme activity or, ideally, by demonstrating the presence of mutations in the alpha-fucosidose gene.

Life Expectancy:
Individuals with Fucosidosis Type I often die in childhood.  Patients with Fucosidosis Type II may survive into adulthood. 

Treatment:
There is no cure for Fucosidosis.  Treatment is limited to reducing or controlling the symptoms of this disorder, for example, medication to control seizures. It is encouraged that individuals with Fucosidosis routinely see their genetic counselors, neurological, ophthalmological, and other specialists as symptoms arise and to keep symptoms controlled.

Patient Groups:
International Society for Mannosidosis & Related Diseases
P.O. Box 328
Dexter, MI 48130
www.mannosidosis.org
tel: (734) 449-8222
fax: (734) 449-2282
Terri Klein, Executive Director
info@ismrd.org