Fucosidosis is a lysosomal storage disorder caused by deficiency of
alpha-L-fucosidase. A biochemically and clinically well characterized canine model of
fucosidosis exists in a colony of English Springer Spaniels. To facilitate its use as a model for gene therapy and
enzyme replacement therapy in lysosomal storage disorders displaying neurological symptoms, isolation of the canine
alpha-L-fucosidase cDNA was undertaken. Both the nucleotide sequence and the predicted amino acid sequence of canine
fucosidase show high levels of identity with the human and rat sequences.
Fucosidosis dogs were found to have a greatly reduced level of
alpha-L-fucosidase mRNA when compared with normal dogs by Northern blot analysis. Direct PCR sequencing of products generated from
cDNA demonstrated a 14-bp deletion in
mRNA from affected dogs. This deletion creates a frameshift mutation and introduces a premature translation
termination codon at
amino acid position 152 and was shown to correspond to a deletion of the last 14 base pairs of exon 1 of the canine
alpha-L-fucosidase gene. Rapid PCR-based screening for the mutation has now been performed on genomic
DNA from dogs within the colony, enabling detection of both carriers and homozygotes.