alpha-L-Fucosidase in normal and deficient individuals

Deficiency of the enzyme alpha-L-fucosidase has been demonstrated in peripheral leukocytes, cultured skin fibroblasts and long-term lymphoid lines from two sibs with fucosidosis 2. Reliable identification of heterozygotes for this disease was accomplished by enzyme assay of mononuclear cells isolated from peripheral blood. Isoelectric focusing of alpha-L-fucosidase isozymes in leukocyte extracts from normal individuals revealed a common polymorphism which was shown to result from two autosomal alleles at a single, autosomal locus. Evidence was obtained for a third, "silent" allele segregating in the family of the two affected children. It is probable that the disease fucosidosis type 2 results from homozygosity for this "silent" allele. Preliminary experiments have shown that cultured skin fibroblasts from deficient individuals can incorporate and retain purified alpha-L-fucosidase added to the culture medium.