Alpha fucosidosis is a lysosomal disease affecting dogs characterized by severe and progressive neurological degeneration caused by a deficiency in an enzyme called alpha-L-fucosidase involved in the breakdown of complex sugars.
Symptoms usually appear between 12 months and 18 months of age and include loss of balance, muscle tremors, circling, nystagmus, jaw chattering, change in temperament, loss of learned skills, difficulty swallowing, regurgitation, and weight loss.
Unfortunately, the disease has no cure, the symptoms are severe and progressive, which in most cases leads to euthanasia before the age of 4 years.
This disease follows an autosomal recessive mode of inheritance.
Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations.
Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.
Canine alpha fucosidosis is a severe neurodegenerative disease affecting English springer spaniel dogs. It is due to a mutation in the FUCA1 gene that produces the enzyme alpha-L-fucosidase, which is found in the lysosomes of cells and is involved in the degradation of complex sugars into smaller sugars. When this enzyme is defective, partially digested substances accumulate in certain tissues and organs and damage the brain in particular.
The molecular defect underlying canine fucosidosis is due to a 14 base pair deletion in the FUCA1 gene sequence, resulting in a reading frame shift and a premature stop codon that produces a truncated and unstable enzyme (Skelly et al., 1996).