Fucosidosis

Fucosidosis, also called alpha-l-fucosidase deficiency, is a rare autosomal recessive lysosomal storage disease in which the enzyme fucosidase is not properly used in the cells to break down fucose. 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.

Focosidosis is one of nine identified glycoprotein storage diseases. The gene encoding the alpha-fucosidase, FUCA 1, was found to be located to the short arm of chromosome 1, by Carrit and co-workers, in 1982.

Types
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.


 * 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. Patients have no vascular lesions, but have rapid psychomotor regression, severe and rapidly progressing neurologic signs, elevated sodium and chloride excretion in the sweat, and fatal outcome before the sixth year.


 * Type II patients have angiokeratoma, milder psychomotor retardation and neurologic signs, longer survival, and normal salinity in the sweat.  The disease often appears between 12 and 24 months of life.  Affected children usually have mild coarsening of facial features, abnormal bone deformities, mental retardation, and an enlarged liver, spleen and/or heart.  Twisted blood vessels within the membrane covering of the eye and inner eyelid are characteristic features of Type II Fucosidosis.