Fucosidosis

Fucosidosis is a rare metabolic disorder caused by decreased amounts of the enzyme a-L-fucosidase, which results in the accumulation of fucose-rich storage products within many organs, including the brain. Fucosidosis occurs in English Springer Spaniels and has a worldwide distribution with reports from Australasia, the United Kingdom, and North America. The disease is transmitted as an autosomal recessive trait.

Clinical Signs of Fucosidosis

Clinical features include mental retardation, enlarged heart (cardiomegaly), seizures, defective bone formation, progressive neurological deterioration, and early death. From 6 to 12 months of age, affected dogs may be anxious, apprehensive, and slow to learn. Skin abnormalities are often seen. The most notable skin findings are tiny purple or red raised cutaneous lesions that are initially found on the trunk but progress to cover most of the body. Hearing, visual, and menace deficits may develop from 18 to 24 months, followed by severe incoordination over the next 6 months. During the third year of life, the bark frequently becomes monotone and hoarse. Death is not uncommon in animals 3 to 4 years of age.

Fucosidosis is a lysosomal storage disorder. Lysosomes are membrane-bound vesicles containing hydrolytic enzymes (such as proteases, phosphatases, glycosidases, lipases, and nucleases) that function in digesting intracellular and extracellular substances.

Late onset of signs may result in misdiagnosis as a primary behavior problem or acquired neurological disease. Fucosidosis is inherited in an autosomal recessive manner, and carrier dogs are clinically normal. Thus, the abnormal gene can become widespread in a population before homozygous-affected dogs are produced.

Diagnosis of Fucosidosis

The disease can be diagnosed by a number of different means, including blood and urine tests and rectal biopsy. There is currently no treatment for the neurological or other systemic manifestations of fucosidosis. Bone marrow transplantation into affected dogs has shown that stem cells can provide enzyme producing daughter cells to the central nervous system, altering disease course. Polymerase chain reaction analysis (PCR) is used to amplify the mutated region in the gene encoding alpha-L-fucosidase. A PCR method can be used to identify dogs affected with or carriers of the autosomal recessive disease fucosidosis. Using this test, fucosidosis can be controlled and ultimately eradicated from a particular dog population.

Adapted from:
1. Neuroradiologic Findings in Fucosidosis, a Rare Lysosomal Storage Disease. James M. Provenzale, Daniel P. Barboriak, and Katherine Sims
2. Genomic screening for fucosidosis in English Springer Spaniels.Skelly BJ, Sargan DR, Winchester BG, Smith MO, Herrtage ME, Giger U.
3. Fucosidosis in a family of American-bred English Springer Spaniels.Smith MO, Wenger DA, Hill SL, Matthews J.
4. Storage Disorders. K. G. Braund